We've been to Y'stone a number of times from Kentucky and can't get enough. We always stay at Grizzly Rv Resort in West Yellowstone. It's so close to downtown you can walk to groceries, restaurants and entertainment from the RV Resort. I always reserve a car right there in town and pick it up when we arrive. It's a short walk from the resort as well. With so few days you'll barely have time to do a drive through of the park in general terms. Use the park map and you'll see the most popular spots to visit for your first trip. Cell service is great and the resort has free wi fi.