That sounds like a wonderful trip.
My recommendation is to see things that you might not ever get back to... so don't spend your time on things close to home. Montana and Wyoming are a far piece from NY. If I were you I would beat feet out west and have lots of time to spend there.
Good info on MT & WY in this recent thread.The folks in this discussion don't have a lot of time, but you will have time to see everything listed and explore in depth.
If you search on this forum you will find lots of info. I also strongly recommend that you get a couple of in-depth guidebooks like the
Moon guide to Montana, and some for other states on your route. It will help you get familiar with the areas you will be travelling through.