Yellowstone, America's oldest National Park, has been on my list of places to visit for many years. It's remote, rather expensive, and you're stuck with roughly mid-April to October to visit, unless you want to stay in the Old Faithful area all the time.
Nevertheless, even avoiding Winter, thorough planning is required to get there and find affordable accomodation. If you want to spend more than a night in the park, you're required to book via a travel agency for the double price, as the bus tour operators and travel agencies secure all rooms as soon as reservation opens. Well, unless you want to stay in Mammoth, but that's in the North of the park and rather far away from the main attractions. Another alternative would be staying in West Yellowstone, but that's not much cheaper than booking a room directly in the park.
What is the right time to travel? In my opinion the time between mid April to Memorial Day, or from Labor Day to mid October is suitable, with some roads probably still being closed for Winter until end of April and the concessions and lodges closing mid of September. Avoid main season in between: it can be very hot in July and August, and the park is crowded with tourists.
We decided to go one week after Labor Day, as we've been told that this is the best time observing wildlife.
The remaining question: how to get there? Hotel or RV? We decided against the RV this time, as we planned for a lot of hiking in the park. With a car, you can get on the road much faster in the morning, also parking an RV full with food for a whole day or over night in bear country wouldn't be a wise thing to do. Furthermore, traveling long distances with an RV in one go, especially over Wyoming and Montana state roads, is not much fun. Taking I-15 from Salt Lake City to West Yellowstone would be bearable, but that's the most boring alternative to get to the park. Also that would require renting an RV in SLC. I've heard reports that made me ruling out that option. Most visitors from Europe start from Denver. The RV rental stations there have a much better reputation, but even choosing a closer entrance than the North-East one near Red Lodge it would still be an additional day just driving.
So we decided to fly to Salt Lake City, rent a car, spend a day there, and without hurry, take the scenic way to Yellowstone.
We, that were Kayjay, Lynard and myself this time. A smaller group than usual, but hiking with a larger group requires even more planning ahead.