RE: could be cold still in the high country.
Re: Reservations, I have yet to do reservations for a park or any place when traveling & vacationing. Only execptions were when we planned on meeting halfway between North Dakota & southern New Mexico to pick up our Scamp
from my son who picked it up at the factory for us. We make reservations at a private campground in Loveland, CO. We made reservations when my son & family were planning on being in San Diego area last spring, but had to cancel them when their plans fell apart. We have gone all over the country camping, mainly in the western US and Canada & some in the mid-west as well. Never had a problem, except in California in '06 but lucked into a nice site anyway. Some of the state parks try to make it hard on those of us who like first come first served it seems, but still can do it. Nat'l parks are easier to do without reservations still.
Traveling in the west with a TT or motor home since 1986.
Report of our trip to Yellowstone this August: http://www.rv.net/forum/index.cfm/fuseacti...id/23076903.cfm