How Chowish are you looking for in that price range? When our son was born right before Thanksgiving two years ago, we did a casual Thanksgiving at Cracker Barrel, and we had a great time. There's one in Altamonte Springs on Douglas Ave.
You might also call and find out if TooJay's in Altamonte Springs will be open Thanksgiving Day. I know they are open on Christmas, because we have been on Christmas (but it's a Jewish deli, so that may be why, but if Christmas, then maybe Thanksgiving???).
3316 Daniels Rd, Winter Garden, FL 34787
I've heard that in Winter Park the following are open: Park Plaza Gardens, Ruth's Chris, Nelore and Chez Vincent. I'd imagine PPG would probably offer a traditional Thanksgiving option. CV gives traditional options in addition to French dishes: http://www.chezvincent.com/downloads/Thanksgiving_Menu_2010.pdf
Park Plaza Garden's
319 Park Ave. South, Winter Park, FL 32789
533 W New England Ave, Winter Park, FL 32789