We have been at both of those times. The Christmas decorations are wonderful, glad we've been able to experience that. But we've become Jan vacationers! We don't think it's crowded in Jan. We are considering the same Jan week as you are, that's the week we went this year, however, we may try Jan 11-17and try to land in between the New Year's mob and MLK holiday. In 2007 we went for a long weekend at the end of Jan (25-29 I believe) and there were no crowds at all, we walked onto every ride (except Soarin) with no waits ever. Have fun!