I spent a little over a month on the road last year just winging it. It's the best. While I agree that the big destinations are harder and harder to visit due

I spent a little over a month on the road last year just winging it. It's the best. While I agree that the big destinations are harder and harder to visit due to the crowds, there's a lot to see out there that isn't "on the map", and some of my favorite stops were the unexpected trailheads, lesser known national parks without as many facilities, and smaller state parks I encountered along the way. With a different kind of planning (i.e. vehicle/supplies/camping gear), winging it will still be possible, but "book a trip to X major park on a whim", not so much.