Best way to stay off Interstates. From FL to Rapid City, SD

Since you are a Good Sam member, they have a trip planner on their website. Google maps also allows you to select different routs to a destination. As said before the avoid highways on gps will work, but it could send you on a very long detour to get from point a to b. Best to get a good interstate map like the Truckers map and plan your own trip. We like to get off the highway as soon as possible, but generally have to take the highway for some part of our trip.