Park City
The most complete place to learn in America, and the clear pick.
Park City is enormous, yet a huge share of its terrain is gentle, so beginners get acres of green runs and long, confidence building cruisers rather than a single crowded nursery field. The ski school is one of the best resourced in the country, the base areas connect to a genuine former mining town full of restaurants and easy evenings, and the light, dry Utah snow is forgiving under new skis. Salt Lake City airport sits around 40 minutes away, the shortest major transfer in American skiing.
It takes top spot because it pairs world class teaching and endless gentle terrain with a real town and the easiest access of any big US resort. The trade is price, since a learning week here is a premium booking.