Maybe not the cheapest to get to but Grand Targhee has probably the nicest beginner area I've seen at any ski resort. We didn't use the ski school but my wife did pretty well there last year. I also seem to recall her doing well at Alta but that was way back in 2010. The flights might be surprisingly similar to SLC though. From any of the airports in the region I can fly to Jackson Hole for a few buck more than SLC and I can fly to Bozeman cheaper than I can Denver.