Yellowstone campgrounds

The options outside the park offer more amenities, full hoookups, some places have pools and/or game rooms for the kids, laundry, some (West Yellowstone especially) options have access to dining, shopping, more of the comforts of home. The options inside the park offer more of a wilderness experience, especially some of the smaller campgrounds. The more time that one spends inside the park, the greater the chances of seeing wildlife. Oh, I guarantee that where ever you stay, once in the park, you will see buffalo, and probably elk and pronghorn, and maybe bighorn sheep, but more rare are wolves and bears. Staying in the park also offers a more personal experience within the park, as once it starts to get towards evening, the crowds thin. There are evening ranger led programs too.