It depends on when you're going; they're shutting Tusker House down, and, if you go when it's closed, the answer is "nowhere" for the AK. For the MK, I know that the Plaza Restaurant does a nice big salad. I'm not a huge salad fan. For that reason, we don't eat at the MK; the options are too limited for us. We just hop the monorail to Epcot - the Sunshine Seasons Food Fair has decent, semi-healthy counter service food.
Cheers!
Heather W