When we returned from Yellowstone in our 2350 last year we used the East entrance and stopped in Cody, WY for a few days at the KOA (there's a shuttle to most of the major attractions and a bus to the Rodeo).
In addition to watching the Gunfight at the Irma Hotel and taking a Trolley tour, we went to the Rodeo (every night from June 1 through August 31) and Buffalo Bill Historical Center. Worth the ride is the Chief Joseph Highway to U. S. 212 and over Beartooth to Red Lodge, MT (& back to Cody).
Cody is a great little town, very patriotic and friendly (and the Wyoming Steak House had a truly wonderful steak).