What do you define as "west" to us, Montana is "east".
Seriously, though, as long as you're travelling before or after the school summer vacation, reservations are not necessary - except for major attractions like Yellowstone.
Out here, we've found that, if you leave home on Sunday and plan to head home again Friday, there's no problem. If you plan to stay over a weekend during school vacations, certainlly inquire about availability. We've often checked in a CG on Thursday before a holiday and have been able to stay through Tuesday without reservations.
Frank and Eileen
No longer RVers or FR owners