We love the bar at the Yak and Yeti in AK - just walk into the restaurant and it's past the hostess station on your right. You can sit there, cool off, and order drinks. We usually end up getting an appetizer too because they are so good, but not mandatory. Also love the outside safari bar next to the Tusker House restaurant.
We love to bar hop at the MK resorts before we head over to Epcot for the night - Tambu Lounge in Poly for a Kona, The Wave in CR for the new organic beer sampler, and Artist's Point inside the WL, next to the restaurant. Only they don't open until 4pm.
Swan and Dolphin have tons of places to get drinks - there's a lobby bar in the Dolphin and Il Mulino in the Swan has a big bar. The pool bar is great but it closes at 10 - although often the bar tender will stick around longer if people are out there. The Crews Cup Lounge in YC in a decent bar - it's next to the Concourse Steakhouse.
Primetime in DHS - there's a separate door to the left of the main entrance that takes you directly into the bar. Seating is very limited because it's usually packed with people waiting for their tables, but if you hover around long enough, something will open up when tables are called.
There's also the bars on the Boardwalk, such as ESPN club and the brewery. Just to name a few that we frequent on our regular visits!