30 day trip out West - Dare we without reservations?

I have been out twice from Alabama with no reservations. I may be going again next year also. The only place we could not stay at was Yosemite. Evidently it is the "inn" place. If you go to Sequoia do not miss Kings Canyon, which is actually a separate park but borders Sequoia. I almost did not go down in the canyon because of a june snowstorm. The canyon was absolutely awesome, like being in Machu Pichu or something like that.