Some good places for A/C or to get out of the rain for while:
AK: Pizzafari, Restaurantasaurous, Satu'li Canteen, Nemo show, Festival of the Lion King show
MK: The shops on either side of Main Street are mostly connected, no place to sit but you can cool off for a while.
Columbia Harbor House is not as hectic for counter service, Gastons Tavern has a small indoor seating area, Pecos Billl's, Pinocchio's is OK and next to It's a Small World to
duck into for a ride with an inside que area. A/C is usually cranked up enough in the Tiki Birds show for us to cool off but a fairly short show. Dumbo rides have an indoor
que now and benches in the kid's play area midway through the que. We avoid Cosmic Ray's since it's often crowded.
HS: Frozen Sing a Long show, Great Movie Ride, Muppets show, Toy Story line is mostly inside but you will be standing. Backlot Express, PizzaRizzo, ABC Commissary for CS.
Epcot: The Land pavilion has Soarin' and the Land rides and Sunshine Seasons CS, can spend some time in there. Electric Umbrella indoor seating. Also the movies in France (seats),
China (standing), and Canada (standing). China movie exits into some connected shops so can spend some time there. The Mexican pavilion inside the pyramid. Liberty Inn
at the USA pavilion has lots of indoor CS seating.
Of course BOG and any park TS restaurants, but need and ADR for those so not available spur of the moment.