My advice is to make park reservations way in advance, and aim for midweek. Personally I would try to stay in the park itself. You can leave and come back, but is a huge park and a long drive in/out of the park. If you spend two days, you may be able to drive in the southwest entrance, camp or stay at the Paradise Inn, and then drive out on the northeast side so you don't have to backtrack. But if you don't mind the drive and the long lines to get into the park, I would probably go for Crystal Mountain. It's a ski resort and it has views, a nice restaurant, and (I think) wifi. Lots of the park doesn't have wifi and the Paradise Inn doesn't IIRC.