I just got back from a 9 day trip to CO and UT, so here are some insights in no particular order that might help you.
- Coverage in CO was better than in UT. In CO I skied at Keystone, Breckenridge, and Vail; in UT I skied at Park City and Canyons. Breckenridge and Vail had great coverage, Keystone not so much. Canyons had pretty decent coverage but Park City was pretty bare.
- In CO I stayed at a AirBnB property in River Run Village at Keystone. It was nice to be right next to the lift for night skiing, but most days I ended up driving to other resorts. If I did it again and stayed at a resort then I would probably choose Breckenridge or Vail. If you want to go cheaper then stay somewhere in Summit County like Frisco, which is fairly close to all of the resorts. If you want to meet others then you could check out the Bivvi hostel in Breck. I haven't stayed there but my friend just got back from a week long stay there and loved it.
- In UT I would just stay in SLC. Hotels are cheap and plentiful, and the drive is about a half hour to Canyons or Park City. It's also about the same distance to the Cottonwood Canyons if you decide to do something like Alta or Snowbird.
- If you go to Alta or Snowbird check out the boarding pass program. You can get a half price lift ticket during the week if you register and go to the resort within 24 hours of landing.
Hopefully that helps, let me know if you have any other questions!