Most of the CS spots do have indoor AC seating - we've never had a problem finding a table, but we don't typically go during peak season.
There are a handful of outdoor spots, like Flame Tree at AK, Cantina at EPCOT, Starring Rolls at MGM, but they typically have a good selection of covered seating areas that end of being pretty cool even in the heat.
My favorite CS with great air conditioned seating is Columbia Harbour House at MK. Few people know they can sit upstairs and you can get a great table right against a window and people watch!