I'd take the Dec 12th-Jan 5th period, most schools will be on winter break for most of that period and it will be after Dec 1st so you'll hopefully have some good news by then.
Each place I interviewed gave me a variety of options for interview dates. Most places don't do interviews the week of Thanksgiving a) because their class is already decided at that point b) do you know the field we are going in to? This is the profession of week long holiday weeks.
If you have the option, go on the dec-jan trip.. Shouldn't be a problem at all
P.s. Here's what the invitation to the UCSF interview said this last cycle:
"We will consider rescheduling your interview if one of the following situations applies, however we cannot guarantee that another date will be available. If that is the case, you will either have to accept the original interview appointment or have your application canceled. All requests to reschedule will require the appropriate documentation:
You have an exam scheduled on the date of the interview
You are scheduled to take the DAT on the date of your interview
You have a medical emergency
We regret that we are unable to offer rescheduling for other reasons. "