Get a Walmart Rand McNally Atlas. Shows all the Walmart stores and whether they have gas stations. The Atlas shows parks and points of interest.
I use www.mapquest.com or www.googlemaps.com to route
I use www.woodalls.com for campgrounds then check them out on www.rvparkreviews.com before final selection.
Stop at state welcome centers and look at their books and brochures.
Once we decide on stops I search that area for things to see and do.
Detroit - Ford Museum
Mackinaw Bridge and Island
Soo Locks at Sault St Marie - watch ships go through the locks. (free!)
Whitefish Point Michigan Lighthouse and Shipwreck Museum (Edmund Fitzgerald)
Mount Rushmore SD
Branson, MO
Corvette Museum and Corvette Factory Bowling Green KY.
Once you get your route nailed down, let us know and we can recommend campgrounds.