Definitely not something I'd recommend. Sandy is deep in the suburbs--if you stay there and want to go to a National Park for a weekday, you're going to deal with heavy morning traffic, then 3+ hours highway driving each way once you break free. And if you do get a powder day (and the roads up the canyons stay open), the massive crowds will show up (same problem with the highest-elevation Colorado resorts). If you want to set up a base and decide day-to-day whether to ski or visit parks, Brian Head is a solid, affordable choice (and they're open until mid-April). They don't have super-steep extreme terrain, but I think you'd have fun for a few days at least. It's adjacent to Cedar Breaks National Monument, and a very easy drive to Zion or Bryce. Grand Canyon and Capitol Reef are farther, but the drives are magnificent. If you book some nights in Sandy or up in Little Cottonwood Canyon, I'd recommend skiing those days whatever the weather brings, then relocate for your park-hopping.I'll have a good look at the pricing and pick. If I stayed in Sandy would I be able/possible to visit national parks from there on the warmer days? I am researching but your experience would assist greatly.
As we get more details on what you're looking for, honestly Mammoth seems like the best bet--that's why everyone keeps bringing it up It's closer to Vegas than Sandy is (and much closer to LA, of course), doesn't have as bad a powder-day crowding problem as the more urban areas, it's a real ski town, and it's got tons of terrain.