We have been to Alta (this January) and are going back for first 3 days in April, but before that based on suggestions of folks here, going to Solitude, and right now plan is to hit Deer Valley too just before we head into Solitude for 3 days or so. Going with my 6 year old who is a pretty solid skier, experienced with big-mountain skiing. Objective is to stay in ski-in/ski-out so can recommend from experience Alta Lodge (great for kids, have a kids program where they have their dinner at 530pm and then hang out with young staffers till 8pmish) and going to try out Inn at Solitude at Solitude. For Deer Valley, lodging still up in the air. Note nothing is that inexpensive though Alta you get half-board, i.e. breakfast and dinner included (there is a 15% service charge plus a hefty 10+% sales tax all additional) but the Alta Lodge was great with my boy as was the instructor. We had a blast. Folks here have recommended Solitude for kids, so we are going there too. Deer Valley is just to experience those famous groomers.
In terms of deals, Snowbird is the best but in the words of the highly respected and experienced Mr Bob Peters on this forum(look for threads on steepest slopes, extreme slopes etc) , Snowbird is the consistently steepest mountain he has ever skiied and the man lives in Jackson Hole, Wyoming. He knows his slopes and terrain with remarkable precision, something to think about.
ps: Dad is an intermediate skier.