Thanks guys:)
Our son has brought over some mapbooks of SW area, but looks as if I need to get some for further East (& possibly North). It is a huge area (compared with Scotland!)and although we want to see as much as we can in the time, we also want time to relax and enjoy the areas we visit. We made the mistake the first time we went to Europe of travelling too much and passing places by. (6000 miles in 6 weeks) We are putting a limit of about 2,500km on the trip which we think should give us enough time for both travelling and relaxing.
I now have lots of places and campgrounds to look up and will continue my research.
BTW we arrive just before Labor Day weekend - is it necessary to book ferries and campgrounds before we arrive?