I'm with DangerMouse--love the GCH lobby and the adjacent Hearthstone lounge! In the lounge, you can order a nice cocoa or something, plus they have games to play, a fireplace, nice comfortable couches and chairs, and a lovely environment in which to enjoy it. The lobby is also very nice for reading and relaxing, listening to the music (there is often a piano player), and just watching the comings and goings. I like to get an ice cream thingy from Haagen-Daz (right across the way) and eat it there.
My favorite spots in the parks: There is a food stand in front of HM that sells salmon salads and soup in a breadbowl. Looks like a shack and is next to the water. There is a path that runs behind it and takes you past the flume that exits from Splash Mt. There are some nice tables along that path and it's fairly secluded. You're right on the water, too.
I also like the decks behind Hungry Bear.
I like the Coke Corner area. That spot near the Ride Wait Times board, where they have the DVC stand, is usually not crowded and a good place to see the hub activities.
Sometimes I just take a break by going through the Tortilla Factory tour and the Sourdough Bakery tour in CA. Plus you get a bonus free snack.
Not sure if they still have it open, but the Golden-something in CA had an exposition of the CA expansion. There is a movie they show and there are benches to sit on.
The Billy Hill show in the Golden Horseshoe is a fun place to sit for a while, enjoy a great show, and eat if you're so inclined.