I’ve read Homage to Catalonia and For Whom the Bell Tolls. What are some great non-fiction books on the Spanish Civil War? I’m also interested in how Franco starts out as a fascist but was able to hang on and survive into the 1970s.
It kind of depends on what you're after. The standard academic overview is Hugh Thomas, The Spanish Civil War (the 2003 edition is best). Another, slightly more pop-history option is Antony Beevor's The Battle for Spain. Helen Graham is a serious scholar and her The Spanish Civil War: A Very Short Introduction gives a credible brief overview, but suffers (like all of the VSIs) from a lack of referencing. If you're after something about a more specific aspect of the conflict, let me know!
With regards to Franco and Spain post-1939 (it's worth noting that Franco's relationship with fascism was complicated, and it's far from unambiguous that it's a good label for him - this came up a couple of weeks ago), Stanley Payne's Fascism in Spain, 1923-1977 is probably the classic text on the subject. Payne's relatively conservative views might be balanced from the left through Paul Preston's biography of Franco.
Spain in Our Hearts pays special attention to international volunteers, but is a compelling read and a decent overview of the basics, in my opinion. That said, I'll admit I'm a casual and nowhere near the expert /u/crrpit is on the subject.