For the last three years, we have been in Florida during the same time frame. Weather wise, completely agree with poster above.
Regarding flights, I highly doubt you will see a DING for your outbound flight. In fact, when SWA releases the week between Christmas and New Years, the lowest fare buckets show unavailable . You might want to consider Airtran for that flight.
Inbound, you have a slightly better chance for a DING, but might have better luck with a SWA seat sale . We flew on SWA MCO-BUF Jan 6/07 non-stop for $59 each (seat sale, NEVER saw a DING for this date). We had set up car rentals to be dropped off at MCO TPA and Fort Myers (RSW) just in case we weren't able to get a cheap fare home from MCO, but luckily we were.