We love Liberty Tree Tavern, but it is NOT good for large groups. We have eaten there the last 4 trips in a row and the food is great but they are never on time for ADR's and they cannot get big groups right. We had 14 on our trip in 2005 and we were not seated til almost an hour and a half after our ADR's and then we took 3 separate tables just to eat!
It is almost impossible to get reservations there even at 180 days out, because other peoples 180 days out beat yours, you know what I mean? All the restaurants serve the same Thanksgiving fare that night anyways. We went to Mom's 50's Prime Time Cafe this past Thanksgiving and we usually love this restaurant. Not a good choice for Thanksgiving, though. JMO.
Good luck. I know with that many friends and family, wherever you go you will have a great time.