I used to live in Park City & we went back this past spring break. It is very nice up there & Deer Valley is just up the mountain a little further. The skiing is very good & there is a ton of stuff to do off the slopes, too.
I used to live there as well and had my passes at Park City which is the best vacation area. My favorite area to ski was actually Powder Mountain and SnowBasin which are by the small town of Huntsville and I used to clear runs at Powder Mountain in the summer for passes. I would ski on Sundays and have it all to myself. As far as the Cottonwood Canyons which are on the Salt Lake side of the Wasatch I preferred Alta. Kind of depends on where you want to stay, if you want the ski town atmosphere then Park City is the spot. If you want less expensive and stay in town then maybe Alta although the trip up the canyons can be a mess if you have to wait for avalanche control. Not sure how it is now but Brighton and Solitude had too many punk snowboarders and what used to be Wolf, then The Canyons doesn't have as much snow at times and can trash your ski's. If you go to Huntsville you have to eat a Star burger at the Star Cafe, oldest continually operating salloon in Utah.
I haven't been to Utah yet but will be in the next year. I heard the skiing boarding is pretty dang good. If your looking for something new Mammouth mountain California just got a extra 17 feet in the last 4 days but you will need 4 wheel drive to get to the resort now. I am doing Lake Tahoe in 3 weeks and can't wait. Just got back from Breck and Vail and they had amazing snwo for this time of the year. If you want different and haven't been we take a 9 day trip to Telluride every year. No lift lines one of the best snow towns around but it is Colorado but not like Summit county.
Depends on what kind of skiing you're into. If you want to to the touristy thing, easy skiing, groomed slopes, etc, the Park City resorts are the way to go (Park City, Deer Vally, The Canyons). It's Utah's equivelent to Aspen, Breck, Vail. Of those three, Park City Mountain is my favorite. Some good hills there.
If you're more of an avid skiier and not worried about the grooming and the catering, Go to Little Cottonwood. Alta is about the best in the state for that kind of skiing and the best thing about it...no snowboarders. Alta is just up the hill from Snowbird which is also fantastic. Snowbird is pretty big, but again...caters more to the avid skiier/snowboarder.
Brighton and Solitude are nice places too but frankly, it's been so long since I've been to any of those, I don't remember much and don't have a whole lot of insight.
Best part about Utah skiing (for the most part) is that you can stay in the City and easily access the resorts.