Dewey came close to being our president, but my whole life he was only a name on the newspaper. Many also-rans suffer anonymity, but not all - Stephen Douglas, Al Gore, Richard Nixon (v. Kennedy and the first televised debate), George McClellan, Goldwater - but Dewey has never, in my life, been mentioned in any history class. It seems he only has one biography.. And yet his Wikipedia page makes him out to be a fascinating character and the bio calls him the founder of the modern Republican party. Is he remembered in New York? Are there any buildings named after him? What gives? (edit / addition: did he do something wrong? Is his party embarassed by him? It seems he was very progressive for his time)
The fact is, in general, the losing candidates in presidential elections aren't remembered. Yes, people are remembered for the things they do, like losing elections, but also what those events tell us about the larger times and events they inhabit. Dewey defeats Truman is a funny photo, but it also gives us lots of insight into how we as a nation were still transitioning from rural to urban life in 1948 and about labor unrest after the end of World War II. Yes, he was governor of New York, but so were 55 other men, many of whom are also undistinguished in general histories.
From the list you discussed Stephen Douglass and George McClellan are most often discussed in regard to their pre-presidential activities around Lincoln, Slavery, and the War. The campaigns themselves are usually summarized into paragraphs. Douglas actually came if fourth in the electoral vote. Do you really know more about the other two candidates Breckenridge and Bell, other than they lost the election of 1860?
If Nixon didn't go on to become president later, he'd just be the guy who lost the first televised debate. Al Gore is still too much in current events to understand what his long term historical memory will be.
Barry Goldwater is kind of the exception that proves the rule. His importance is driven by his role as a philosophical influence on the Gingrich political movement of 1994 up to tea party of today. I reviewed Amazon's database and I could find any Goldwater biographies published between the 1964 campaign and 1995. But back to the general rule, how much do we know about Hubert Humphery and George McGovern who lost the next two elections?
Stephen Douglas retains probably equivalent notoriety. Consider that his public memory is limited to debates against one of the wittiest US presidents, so holding his own was a big deal.
Al Gore is still a relevant public figure, and his time as an "also-ran" was taken all the way to the Supreme COurt.
Richard Nixon eventually became POTUS.
I wouldn't argue George McClellan isn't especially remembered...
Goldwater is something of an ideological forefather of the contemporary libertarian/small-government GOP movement. He also challenged LBJ, who in hindsight ran up the debt and body count fighting for liberal initiatives and Cold War credibility.
Dewey lost twice to two favorably-remembered presidents. He was good at his job as a prosecutor but was/is simply not seen as a presidential contender.
Yes, there is a thru-way named after him.