Hi N.! You've gotten lots of great advice already. If you want to be absolutely 100% sure that you'll have snow for Christmas, you should look to CO, UT, WY, or MT. I'm from New England, and we often have snow, but there have been years that I drag my snowboard home, only to see mountains covered with mud. If you're planning a big trip in December, go West (in February you can count on snow East, just not necessarily by Christmas).
As for where to go, I HIGHLY recommend Park City, UT. There are 3 different ski resorts within 20 minutes of the town, all served by a bus system so you don't have to drive. You can go to whichever is more your style (look up Deer Valley, Park City Mountain Resort, and The Canyons to see which best matches your needs and desires). Park City and the Canyons are both good for intermediates--I've skied both. Deer Valley is more full-sevice swanky, but doesn't allow snowboards. Also, the downtown area is great, with lots to do for non-skiers or if you need a little break. Groceries, necessities, even an outlet mall are all right there. There's a park with inner-tubing if you want another way to slide down a mountain. Lots to do, very accessible--I've skied all over the world, and Park City is my favorite for families!
Also, if you want more advanced skiing, you can drive from Park City to Alta, which is my absolute, bar-none, favorite place to snowboard on this continent. There is nothing else in the valley, at all, so only stay there if you really want nothing to do but ski and ride. But if you're travelling with others, you can stay in Park City and drive down to Alta for a day trip.
Finally, Park City is one of the easiest ski resorts to get to. Fly direct from Dallas to Salt Lake City, then a 45 minute car or bus ride to the resort. Easy easy easy. You can leave home in the morning and be on the slopes after lunch. The resorts even give you a free lift ticket for that day, if you show them your boarding pass from that morning. Enjoy!