(I'm including little explanations for each one...)
1900: William Jennings Bryan/Adalai E. Stevenson I (D)
This one was actually rather difficult, but Bryan's anti-imperialist stance tipped me to the Democrats.
1904: Theodore Roosevelt/Charles W. Fairbanks (R)
This one was easy at first, but got harder the more I looked at the candidates. Ultimately, though, the similarity between the platforms of the (R) and (D), together with what Roosevelt had already done meant that I voted for Roosevelt instead of the party with an 81-year old (!) VP candidate.
1908: William H. Taft/ James S. Sherman (R)
Easy; Bryan is worn out and faded, and Taft looks likely to continue Roosevelt's policies.
1912: T. Woodrow Wilson/Thomas R. Marshall (D)
It was very difficult to decide between Wilson and throwing my vote away, based on what I knew at the time. Very, very difficult. Ultimately, I decided that Wilson's "The New Freedom" ideas were slightly better than Roosevelt's "New Nationalism" (mostly insofar as the latter would destroy the courts), and throwing my vote away would be pointless, anyhow.
1916: Charles E. Hughes/ Charles W. Fairbanks (R)
Wilson is a SOB. Enough said.
1920: Warren G. Harding/ Calvin Coolidge (R)
This one was hard, with just the knowledge that I had at the time. Normalcy and peace sound good, but some of the Republican rhetoric is really nasty, and I can't quite get out of my head what would happen to three of the participants in the future (especially that running mate of Cox's...). Ultimately, though, I decided that Cox obviously didn't have a chance, and anyways Harding sounded okay.
1924: Robert M. La Follette/Burton K. Wheeler (P)
This one was easy, the other two candidates suck from my perspective.
1928: Alfred E. Smith/Joseph T. Robinson (D)
Two words: Teapot Dome.
1932: Franklin D. Roosevelt/ John N. Garner (D)
1936: Franklin D. Roosevelt/ John N. Garner (D)
1940: Franklin D. Roosevelt/ Henry A. Wallace (D)
1944: Franklin D. Roosevelt/ Harry S Truman (D)
Yeah, like I'm gonna pick anyone else
1948: Harry S Truman/Alban W. Barkley (B)
Dewey is mouthing platitudes while Truman is actually doing things. Sure, he might be facing challenges from both wings of his own party, but with any luck the Dixiecrats will be subdued for a while by their obvious and preordained failure ("we want to be
just the Solid South--Yeah! That's great!"

), so he can go ahead and do great things.
1952: Adalai Stevenson II/John Sparkman (D)
This one was difficult. By this point, Democrats are pretty well established as my go-to choice (like Republicans for RogueBeaver), but Sparkman is a racist bigot and Eisenhower would be good for foreign policy and defense matters, which, well, matter in this election (seeing as how the Korean War is being fought and the Cold War is getting started). However, McCarthyism won (or rather, lost) out, so I dropped Ike. Not to mention Nixon being, well, Nixon (the "Checkers" speech is rather a negative for me).
1956: Dwight D. Eisenhower/ Richard M. Nixon (R)
Stevenson's ideas on the military lost my support, plain and simple. An all-volunteer military just wouldn't work in the 1950s. Besides, Eisenhower was slowly working against segregation, something that the Democrats probably wouldn't or couldn't do.
1960: John F. Kennedy/Lyndon B. Johnson (D)
Easy!
1964: Lyndon B. Johnson/Hubert H. Humphrey (D)
Easier!
1968: Hubert H. Humphrey/Edmund Muskie (D)
Pff. Like hell am I voting for Wallace, or Nixon for that matter. I'm not particularly excited about Humphrey, though; if RFK were running, things would be different (DNC-type or no).
1972: George McGovern/Sargent Shriver (D)
Like hell am I voting for Nixon, again. Not that I like McGovern, either; he's impractical and a dreamer, better suited for a support position. Just a weak field this year.
1976: Gerald R. Ford/Bob Dole (R)
This one was the first tricky one since the '50s. I like Ford enough that I thought I would probably have picked him over Carter; the latter is too inexperienced and overly vague about what he will do as President (plus there's the whole born-again thing, I don't like that all that much, though Carter was alright).
1980: Jimmy Carter/Walter Mondale (D)
It will be a very cold day in hell before I ever vote for Reagan. Not that I particularly agree with Carter's policies, but they're bound to be miles better than a Cold Warrior like Reagan.
1984: Walter Mondale/Geraldine Ferraro (D)
Again, Reagan sucks. Nice that he announced
Freedom, but I'm not going to vote for him because of that.
1988: Micheal Dukakis/Lloyd Bentsen (D)
Hey, I'm a Democrat. Besides, Republicans have been ballooning the deficit and inflaming the Cold War, we need to get rid of them.
1992: Bill Clinton/Al Gore (D)
With no national security threats left, we need people who will work on the domestic front (ie., Democrats).
1996: Bill Clinton/ Al Gore (D)
Not gonna vote for Dole, plain and simple.
2000: Al Gore/Joe Lieberman (D)
Not gonna vote for Bush. Besides, he is pretty much opposed to everything I believe in.
2004: John Kerry/John Edwards (D)
Would have OTL. Iraq War? Bad. Bush's domestic policy? Bad.
2008: Barack Obama/Joe Biden (D)
Nearly did IOTL (confusion and not being registered in the precient where I spend most of my time around election day meant that I didn't). No way I'm going for Palin or McCain.
DudeAlmighty said:
I know you said not to vote for third parties, but I figured TR, LaFollette, and Perot would be alright since they were major party candidates.
Actually, he specifically excludes 1912, 1924, 1968, and 1992 from that limitation

Although why does he think anyone is going to vote for
Wallace?