We took our grandkids out west this summer for month. We left July 15th and returned August 15th. Since we had our grandkids and we were visiting very popular sites in Colorado, Utah and Arizona I made reservations a month in advance at the best campgrounds in these areas.. In retrospect, I believe I could have have just showed up at any of the campgrounds and got a good spot.
If it was just the DW and I, I'd risk no reservations, but if it's a carefully planned trip with grandkids, I'd still make reservations.
