Thanks

I've given it some thought and a roundtrip seems like a doable and nice option

What do you think with the route (approx) given below, is april or may a better option to start?

south (starting in new york, not SF)
https://roadtrippers.com/trips/5764394
north
https://roadtrippers.com/trips/5807385

Still need some planning what to see/do after yellowstone since I haven't given it much thought yet.