I am going to Yellowstone in mid July too. We are taking the long route. We are flying into Rapid city SD, spending a few days at Mt Rushmore, Jewel cave, then enjoying a nice drive to Yellowstone via Devils tower. Eastern Entrance.
When we exit we will go out the north and drive thru MT and go see Little Big Horn and then end up on a dino dig back in South Dakota. Then fly back out of Rapid City.
I know it is long and a lot of driving, but we are taking 10 days to do this. Should be fun.
Are you camping in yellowstone or staying at one of the lodges?