Outer Rim at the Contemporary
Tambu Lounge at the Poly
Raglan Road at DD
Belle Vue Lounge at Boardwalk (but only before the convention lets out)
ESPN at the Boardwalk
Rose & Crown (UK/Epcot) can be fun if it's not too crowded; otherwise, grab a beer to go and find a bench in the English gardens
Sommerfest (Germany) Not a bar, but they have draft beer and licquers. There's also a beer cart outside by the lagoon.
Tune-In Lounge (Studios), but avoid it during lunch and dinner hours
Sci-Fi Dine-In is fun for beer & appetizers
The best bar is long gone (Catwalk Bar). All the stuff is still up there, though, so maybe someday....