Don't get to the NorthEast too early! From personal experience in 2004, I found that none of the public or even private parks were open until very close to Memorial Day and I very often had to use WalMart until I arrived at relative's driveways
A Woodall's to research open/close dates for RV parks would be very handy, as well as a Rand-McNally from WalMart which lists store addresses (aka The WalMart Woodall's
).