I remember riding the Wildlife Express Train on a very humid day and the conductor/announcer/whatever on the train mentioned over-and-over-and-over that the Conservation Station was an air conditioned building. (Between the controllable cameras, slate of animal checkups/surgeries, and they still had the Rafiki animal films, spent a good amount of time that day in that A/C).
Last trip I found the best a/c was found in the stores (and for some peculiar reason the store in Norway where they were selling Helly Hanson gear was the coldest room in the swamps). I recall walking past the Emporium in the MK, feeling a blast of cool when I past every open door. Attractions, on the other hand, it wasn't unusual for some to have a temperature that gives you a 'clammy, sick in bed feeling' - kind of like it is 2am in a resort room and the motion control shuts off your A/C
And for the record, since you brought up Tomorrowland attractions, even 2am in a resort room with the A/C off is better than being in Stitch.