The place is fantastic, but it's a few hours drive 1-way from Yellowstone in Dubois, Wyoming.

After that, I like to go without a plan. Just take the map, drive the loop, go where the crowds aren't. Hike, Take pictures, eat, etc.

Always arrive early to avoid the gate lines.

Other than that, Yellowstone is great. It only really sucks if you get stuck at the entrance.