I agree with the TTA, one of my favs.
Lets see;
MK: TTA, a shady spot anywhere to people watch. I also enjoy the train, sometimes will stay on it for 4 round trips just to sit and relax.
Epcot: American Pavillion, UK area, Japan, also again, sounds silly, but Spaceship Earth, just again, to relax and cool off.
AK: pretty much any place that is shady, but also like to sit in the outdoor area of Tusker house, especially early in the day, just to sit and people watch.
MGM: don't have a fav spot, again mainly just anywhere there is a bit of shade and good people watching.
I do enjoy sitting near areas where there is live music/shows going on just to sit, relax and listen.
I use Epcot as my evening, after 3 to 4 days of park hopping, to just sit, and I mean sit, for like 3 to 4 hrs, waiting for Illuminations. I usually sit in Italy, but last trip in 2004, I sat in the Canada area, had a nice bench, next to a stand the had popcorn, soda, and beer, and again I was there for min of 2 hrs.