Yellowstone is HUGE! You need to stay inside the park or you will be weary from driving to and from base camp daily. Fishing Bridge is the only one with hookups if you need hookups. It probably is booked solid by now. Many of the other campgrounds are very nice if you don't need hookups. You can divide your visit into 5 different drives for 5 different days and see so much!
Entrance and Road openingsBe sure to take one day to see the Grand Tetons and another to drive the Beartooth Pass (if open).
WARNING!! Once you've been here you will realize you didn't see 1/10 of the park and you will want to come back many times!!
Love this place!