Suggestions for solo travel in western N. America?

Santa Fe will be quite cold in December usually. It's high desert, so don't let the whole "desert" thing fool you. Snow is also a possibility as boxermom mentioned. There are some well loved spas in Santa Fe though and you can also day trip to a couple interesting places from there.

If you're looking for a short flight, there's always Portland, Seattle, or San Diego. A little bit longer and you could do Dallas (nice spas, great shopping) or one of the other larger cities in TX (haven't really been to those much, so I don't have any opinions on them).
 
Love, love love Vancouver! It is gorgeous and the food (you know me and food) is fantastic! I'll send you restaurant recommendations.

Victoria is a lovely, lots of gorgeous architecture and definitely a place to visit. Granville Island is also good, they have a farmer's market and I usually buy my smoked salmon from this nice lady away from the main building to lug back to the US.

The shopping on Robson is pretty good - they have lots of stores there and what I like the best is that they have lots of petite sized clothes. Pacific Mall is also near there and has lots of shopping.
 
I think that everyone here has suggested a place that I've had an interest in or have been to in the past. Thanks so much for the superb ideas! I still think Vancouver is my frontrunner....now if I could only get past the guilt of spending the money on something as indulgent as a solo trip and sticking my hubby with the kids for 5 days....

How do I get over this mommy guilt and finally do something nice for myself?!