Hi Bostongrl25: As a Northerner and a part-time Snowbird, I sooo get this dilemma.
Indeed, jeans would be the “ideal” item to wear when leaving this end of the world, but totally impractical at the other end.
A lot will do with WHERE your layover city is… is it in the North, or the South ?
For example, we usually get a direct flight to Florida, and then have to catch our second flight from there. Florida in December and generally speaking you’ll have temps in the 60s or 70s F (Daytime HIGHS) and although Night-time LOWS will be quite different, once you get to the Caribbean you’ll find Daytime temps to be higher, and the Night-time Lows to be what Florida sees during the day (so IMO best to aim for clothing suitable for aprox 70 F)
Generally speaking, Mr TTR and I leave Canada bundled up. And make our “costume changes” enroute.
So typically Jeans, Sweaters, Boots and Winter Coats out the door here… and then leave the Outerwear in our car parked at the Airport (although our home city Airport does have indoor parking, so doing so is convenient). If that isn’t the case and you have to park off-site, and take a shuttle (and worry about digging your car out of a snow bank upon your return), then that might not be a practical solution. I do know there are “some” Airports that will also allow you to check your Winter-gear when you leave, and pick it back up when you come home … so that is another option, and worth investigating (call your Airline for more info, or check out the Airports Official Webpage)
When we arrive in Florida, we switch into shorts or khakis / chinos. I personally prefer long pants just because the planes tend to have mega air conditioning so I find myself chilly otherwise… which is also a good reason to pack along a sweater in your carry-on luggage as well. Zip-off Pants are also an ideal alternative (you really don’t want to opt for a dress or a skirt IMO because they don’t travel well… if LOOKS are important to you however, for whatever Resort you are destined for, you can always switch clothes again in the Destination Airport before making the transfer to your Hotel)
If doing a costume change in your connecting city isn’t an option, then I suggest that you leave home in lighter weight pants (as noted above) and wear layers, so you can add or remove on your flying days as necessary.
Hope this helps,