Grizzly is our choice...you can walk into town if you like. Lots of stuff in the park for the kids to do too.
Picture Yellowstone as the figure EIGHT with the northern circle having the most wildlife. You'll want to cruise through that area in early morning and/or early evening for best chance of seeing everything. The southern circle contains most of the geysers including Old Faithful. They post the time for OF eruptions so you can pick the best viewing platform for you. I sat down front of the bleachers with the kids while Deb and our older kids sat in the upper dining area of the lodge. Both are excellent for viewing and pictures.
Take your time to tour the park. We visited every side road and nook and cranny. We saw deer, elk, moose, bears, beavers, a nest with 3 baby owls, wolves and of course Bison. Pictures are posted on our blog, but you'll have to scroll backwards to find them. Pictures of Grizzly are on there too. We spent two full weeks touring the park. A geezer card will get you admission to one of the greatest shows on earth.....Dennis