I can strike several locations off of your list:
I live in
Vancouver, right up the road from Seattle. You don't want to be in the Pac Northwest at Christmas unless you like low, grey skies and rain. The only reason to come is to ski (Whistler), but December is a bit early in the season.
I lived in
Montreal for four years. Great city, but you'll be up to your eyeballs in snow. Go in the summer when the streets are throbbing with the best outdoor festivals imaginable.
In terms of places to go to, I know that you're American and have restrictions on going to Cuba, but is there a way that you can get to Havana? I would love to spend time there and elsewhere on the Island, particularly before Fidel buys the collective farm. The food is lousy though, unless you can live off of rum and cigars.
I love
Turkey - it's a wonderful mix of ancient history (stunning Greek and Roman ruins), Ottoman history, blended Asian/European cultures and gorgeous landscapes. It's affordable, easy to get to and a wonderful place to travel. The food is great.
I'll second Roger's suggestion for
India but only if you've got a fair amount of developing-world travel under your belt. It's very full on, but very rewarding and thrilling. Of course the food is fantastic and very varied around the country. I'm particularly fond of the southwest (Kerala state). If you'd like the feeling of southern India but with a lot less intensity, consider the beautiful island of
Sri Lanka.
Southeast Asia is my annual stomping grounds, although it's definitely on the far side of the world from you. I would strongly recommend
Vietnam and
Laos, two of my favourite countries. Thailand I would give a pass. I find it overrun with tourists and not as interesting. The food all over SE Asia is stunning.
Happy choosing!