We almost didn't get into Yellowstone due to bad weather - snowpacked roads. Luckily they let us through but we wouldn't be able to return the same way as they would be closing the road. That meant we'd have a long drive back. Once through though Yellowstone was incredible. The drive back took us from Montana, through Idaho, back to Wyoming, over mountain passes, through blizzards, in the dark for over 3 hours - wondering if you'd find the next road closed due to the conditions. We had enough emergency gear in the car if we had to sleep out the night, but it never came to it. A hot hotel room and a warm bed have never felt so good.