How fun!! Which hotels are you checking out?
I personally think you'd be better off sending in January with a March RSVP date. If you send them in November, they could get lost among all the holiday cards, and the general holiday insanity. I think January is when people start to think about summer plans anyway. And if you've already sent out a save the date, they will have it in the back of their mind. Just my 2 cents though!