All that being said, remember that other people's plans tend to change and there are always last minute cancellations. I heard similar "horror stories" about doing the southeast over the winter. "Make advanced reservations", "stay away from this area" etc. We had no problems planning a couple of weeks in advance, and summer camping in the northern climes won't be much different. Last summer, we decided last minute that we didn't want to deal with Cape Cod on July 4th and made reservations at a KOA close by (but OFF cape). They had several sites available due to late cancellations. As is usual, people make reservations a year in advance on the popular weekends and find themselves unable to go.