The National Gallery in London did a series of 100 podcasts over 10 years. They're about 15 minutes long each on a variety of topics:

http://www.nationalgallery.org.uk/podcasts/

Unfortunately most academic or academic-ish books never reach the volume of sales necessary to make doing an audiobook version of them profitable, which is why you're finding our booklist a bummer. I did a quick breeze through Worldcat for opera history audiobooks, and there were only 2, neither of which I'd recommend. :(

But I enjoyed this book which is pop history but nice, and after I read it I purchased it for my dad on CD, and he loved so much spent the next 2 months insisting I should read it myself. He is earnest but a very poor listener. :)

I don't suppose you like historical fiction? There's tons of that in audiobook.

So I love Audiobooks. I always have one on my iPhone, and a second one on deck in case I finish the first one before I can sync. But... I don't believe I have ever listened to a "serious history book". Narrative non-fiction certainly - Midnight in the Garden of Good and Evil has great narration for instance - but anything halfway academic which for whatever reason I might possibly want to be able to recall something from, go back and check/cite/share/etc., I'm going to read in physical form. I fear that this will often be the case when it comes to other readers of non-fiction. So while I can recommend books, but I don't know off hand what it and isn't available in Audiobook form for much of what I read (A random check shows that if you are so inclined, Richard J. Evans' Third Reich Trilogy is in fact available in audio form, so checking whats in the booklist on Amazon for audio availability might be more productive than you think!)

So that being said, if you are just looking for great stuff to listen to, and want books with a historical bent, which can include historical fiction... then I have listened to tons of stuff I can throw your way.

Shiloh by Shelby Foote is great. It is done with a cast recording, pretty short (one sitting I would venture), and is a pretty enjoyable book. Supposedly his three volume Civil War narrative is also in audiobook form. Hopefully narrated by him, but I never listened to it. It would have to be at least 40+ hours I'd think.

The Amelia Peabody Series by Elizabeth Peters is something of a guilty pleasure that my fiance and I listen to on car rides. Agatha Christie style mystery books set in Victorian/Edwardian-era British controlled Egypt, following a family of Egyptologists. Peters, IIRC, does in fact have a Ph.D. in Egyptology. Also the narrator is fantastic (Barbara Rosenblatt, or something like that, I believe).

Edward Rutherfurd writes giant tomes that center around the history of notable cities. TBH, I can't speak the the minutiae of his historical accuracy, just given the scope if anything, but might be worth looking into for you. London and New York I thought were pretty good. Paris and Russka were mediocre.

Matterhorn by Karl Marlantes is an absolutely fantastic Vietnam era work, based heavily on the author's own experiences but fictionalized. One of the best novels I've read (listened to). Tim O'Brien's The Things They Carried is also pretty good.

In Cold Blood by Truman Capote is quite the classic, and worth checking out. The aforementioned Midnight in the Garden of Good and Evil too.

If you want some straight up ear candy, the Sharpe series by Bernard Cornwell, is all in audio form, and while I confess I never got into them very well, you can't shut my dad up about the Jack Aubrey series by Patrick O'Brian, which is pretty well done narration.

If you are interested in history audiobooks, you do have the option of skipping secondary literature altogether and just listening to some interesting primary sources. LibriVox is an organization that crowdsources audiobooks for works that have fallen out of copyright.

One that I personally recommend is The Interesting Narrative of the Life of Olaudah Equiano. The book is an autobiography of a slave (of which there are only a few). You have to keep in mind that Olaudah was incredibly lucky in how well he was treated (not that he was treated well necessarily, but that his experience was vastly superior to that of almost all slaves). He experienced slavery in the U.K., the U.S., and the Caribbean. I believe I've heard that there is some controversy as to the legitimacy of the beginning of the book that takes place in Africa, but the rest of the story is largely accurate. Olaudah is incredibly eloquent and offers a fascinating perspective.

I don't know how well it holds up as a "serious history book", but Empire of Blue Water by Stephan Talty works really well as an audiobook. It focuses on the career or Captain Henry Morgan as a pirate/privateer for England and keeps the pace and details light enough to lean a little more toward entertainment than academic.

Like some of the comments here, I would never listen to an academic work in audiobook format. If nothing else, it would surely be difficult to annotate or reference.

But online lectures can be worth listening to when on the move. In particular, Jonathan Smele's Russian Revolution: From Tsarism to Bolshevism is a pretty good fourteen part introduction.

Over the past year or so I've been on a binge of history audiobooks available through Audible. I know this is a late post, but I thought I'd list them out here in case anyone stumbles across this thread in the future (like I did). Where possible I've noted if a book is in the AskHistorians book list, or if it's been discussed in an AskHistorians thread.

Classical World:

• The Poison King by Adrienne Mayor. I thought that this was a great overview of Mithridates, and of the Black Sea and Asia Minor regions in general during Roman expansion into the Eastern Mediterranean. I'm not really in a position to assess its historical accuracy, and it did seem to get quite speculative in a number of places, however /u/Almotasim highly recommends it in an AskHistorians post here.
• Zealot: The Life and Times of Jesus of Nazareth by Reza Aslan. This presents a historical account of the 'real' Jesus Christ. While the book doesn't present anything novel (popular history), /u/kieslowskifan suggests here that there is agreement within the history community that the book is plausible and sound.

American Revolution:

• 1776 by David McCullough. This book offers a popular historical view of the initial tumultuous stage of the American revolution (George Washington retreating successfully 101). There's some discussion of David McCullough and popular history in general in the AskHistorians thread here, and /u/kieslowskifan points out that while popular history books may have a degree of bias and offer few new ideas, you can do far worse than David McCullough.

Antarctic Exploration:

• Endurance: Shackleton's Incredible Voyage by Alfred Lansing. This history of Ernest Shackleton's expedition to Antarctica blew my socks off. The account is based on diaries and interviews of the expedition's crew members, and is exceptionally interesting and well-written.

WW1:

• Storm of Steel by Ernst Jünger. In AskHistorians book list. Description from book list: "The best of the German memoir-novels of the war, Jünger's text conveys the experience of a young man who found himself exhilarated and challenged by the experience of combat."
• The Guns of August by Barbara Tuchman. In AskHistorians book list. Description from book list: "A marvelously accessible narrative history of the early days of the war. It does a good job of situating the conflict within the waning era of the Empires, and its combination of solid research and exhilarating prose has more than accounted for the acclaim it has received."

WW2-ish:

• Bloodlands: Europe between Hitler and Stalin by Timothy Snyder. In AskHistorians book list. Description from book list: "Very readable account of the events in countries caught between the Soviet Union and Hitler's Germany during the beginnings of WWII, starting with Ukraine's Holodomor and the political tensions that rose from Stalin's paranoia of outside influence during those events. Really gives you a sense of the suffering of the people."
• The Second World War by Antony Beevor. In AskHistorians book list. Description from book list: "A monumental single volume history of World War Two, coming in at over 800 pages. For those who are unfamiliar with Beevor he is a very accessible historian, who writes on various aspects of the Second World War. Now this is a general history covering the entire war, so don't expect any new revelations or a huge amount of indepth analyses. But he does give a very good overview of all the major campaigns and battles in a nice, easy to read format. If you are very knowledgeable about the Second World War, this book doesn't offer a whole lot, but if you are new to the conflict, you can't go wrong with this one."
• The Rise and Fall of the Third Reich by William L. Shirer. This book came out in the 60's and while enormously popular has been panned by many historians. Shirer is a journalist who provides many good first-hand accounts, however he is very prone to editorializing and injecting his own analysis of German history leading up to WW2. There's a discussion of the pitfalls of the book here. All of this being said, the book goes into a lot of detail about the different players in the Nazi regime and offers an engaging synthesis of a mountain of documentary evidence. Overall its a very interesting listen, and I'd recommend it as a good overview of the Third Reich so long as the listener is aware that it has some notable shortcomings.
• D-Day by Antony Beevor. A very detailed account of the preparations for and aftermath of the D-Day landings. While this comes off as a solid work of history, and many of Beevor's other works are on the book list, I had a really hard time getting through it without a series of maps in front of me. This one might be better off read than listened to.

Cold War and beyond:

• Legacy of Ashes by Tim Weiner. A pretty engaging although quite negative history of the CIA. There's some discussion about it in an AskHistorians thread here.
• The Cold War by John Lewis Gaddis. In AskHistorians book list. Description from the book list: "An excellent introductory book for new readers; clear, precise, great analysis and a must read for those who want to familiarize themselves with the Cold War. The most updated of the Gaddis Cold War series."