Colter Bay is a very nice campground in the Grand Teton National Park.  There is lots of internal hiking to various areas including Swan Lake and Heron Pond to name but a few.   Pack a lunch and take the kids for a nature hike - or hustle the family out there for a wildlife viewing later in the early evening hours. There you will have access to the Colter Bay Marina, a history museum and Jackson Lake for many water activities.  It is a fairly short drive into Jackson Hole, WY.   There are several activities and attractions that can be done in a day trip into Yellowstone.  Or you can camp overnite in Yellowstone and branch out to the other internal areas.