I'm in the early stages of planning a 3 week RV trip to visit Yellowstone and Grand Canyon. I live in the UK and I can't quite figure out what's the best time to come. We'll be travelling with a 3 year old, so I don't want it to be too hot, on the other hand I don't want to be too cold either... My research so far leads me to believe that September might not be a bad idea? And that travelling from north to south might be best? So maybe fly into Salt Lake City and fly out from Las Vegas or Phoenix or?
Also, being european I obviously have difficulties with the distances... How much is it reasonable to expect to do in 3 weeks, if you don't want to spend the whole time driving?
Thanks a lot,