Thanksgiving out in Manhattan?
I've heard of a restaurant that serves family style American. MAIN STREET, I think is the name, on Columbus Ave in the 80's. Check to see if SYLVIA'S @ 126th is open on Thanksgiving. Or Copeland's on 145th. Zarela's, if it's open might be an idea (Mexican, but it may be too expensive).
Too bad you ruled out Chinese. Last year we had Dim Sum in Chinatown on Thanksgiving. It was a blast.