Make sure you double check everything if you're planning a road trip.
Elevation data comes from different sources and may not reflect true
driving conditions, so talk to other RVers if you're concerned about
steep grades. If you're planning to drive in the winter and you want to avoid snow, check the road conditions from Michigan to Florida
. You can also view a 3-D map of Michigan elevation
or Florida elevation
Generally, it's flatter if you pick a route that's farther West, but this adds extra distance to your trip.
You could try I-75 to I-71 to I-65 to I-10 to I-95. That adds a lot of time, but it's good if you are on a leisurely drive and you want to see the Gulf Coast.
Basically, Kentucky and especially Tennessee is where you might have steeper hills to climb. I-65 through Nashville is generally going to be flatter than I-75 through Knoxville.
Taking I-77 through Charlotte, NC is generally going to be steeper as you go through the hills of West Virginia.
Remember to take into account road conditions. Interstates are generally cleared first, so they may be easier to drive if there's any snow.
Last thing is make sure you check your timing through Atlanta because there can be a lot of traffic. Try to get through before 3pm to avoid being stuck in slow traffic.