30 day trip out West - Dare we without reservations?

this year my wife and I took 8 weeks out west from new york setting out in mid may. As far west as hoover dam, north as yellowstone. We visited most national parks along the way. we had no reservations and made out just fine. best advice I can give is to be flexible, get the app called 'allstays' for smart phone or ipad yes it's 9.99 but it was worth many times that, be comfortable to camp without hookups at times, bring plenty of 16g media cards and keep your finger on the button.

joe