I took a 12 week old and we had a great time, but 8 weeks, I think I would prefer to wait a few more weeks. if you are talking 8 weeks at Thanksgiving, then he/she isn't here yet - so you can't really predict how old he will be with any great accuraccy - you could be talking about a 6 week old baby, or a 10 week old - there is a bit of difference between the 2.
We took our dd at 12 weeks and had a great time - it was a bit more hard work, but we enjoyed the trip and I have no regrets. I don't think I would have been so happy at 6 or 8 weeks - I had a c-section, not planned but it can happen, and it takes a good 6 weeks to recover from that, plus sorting out all your sleep and feeding. While I am a big fan of travelling with babys and children, I think I would wait a couple more weeks.
Plus - Thanksgiving will be really really crowded, could you go right before or after christmas or new year? Christmas week is busy, but the weeks before and after aren't too bad - we were there December 1 - 14 last year and it was perfect crowd-wise
Bev