Welcome to RV.Net Ultragolfer, It's been awhile since I've been to Yellowstone! I chose to take I-90 to one of the North Entrances. I went I-90 to Livingston, Montana Mile Post #333 (There is a McDonalds right where I turned off.) I traveled about 30 miles and stayed at an RV Park (right hand side of the road) on Hwy. #89 just before the bridge that crosses the Yellowstone River, into the town of Gardiner. We went in mid October all the Fall colors, snowing every night (The NPS road crew had every road plowed before daylight) lots of animals and beautiful scenery. We camped out for a week at the RV Park I described right on the Yellowstone River. And used our tow car to see all the sights all week! Hands down the most beautiful place I ever been to. Lots of Elk bulging and fighting right at the Mammoth Hot Springs C.G. Ranger Station. You will be able to get anything you need in Gardiner, Gas, food etc. Enjoy