Since you want to see National Parks, put together a list of the parks you think you want to see, and try connecting them. If you don't know which parks, and why you would want to visit a particular park, look for National Geographic's "Complete National Parks of the United States" for capsule descriptions of all the Park Service properties. There are about 400 to consider, not just the few big famous ones in The West.
When you've selected and connected your parks, see which states this takes you through. Then go online to the tourist or visitor websites for each state, see what each state has to offer, decide which things interest you, put those on your route. If you want this information on paper, every state still publishes a visitor's guide, just ask and they'll send you one; they'll send you a new one every year for years, I have seven file boxes filled with this stuff.
There are other approaches, including "1000 Places" books for the U.S., and special interest guides like "Eccentric America" and "Watch It Made in the USA."
Yet another approach would be highway guides, like Michael Wallis' classic virtual road trips for Route 66 and for The Lincoln Highway. There are others that serve better as planning tools, like Jamie Jensen's "Road Trip USA" which has details of what to see for five road trips west to east, six north to south.
You'll find these, and more, at most decent public libraries. You'll also find state and regional travel books.
Sometimes the planning can be as much fun as the doing, but for the pace you describe, you need not plan excessively. With a general idea of where you are going, you get there when you get there.
You find things along the way that you didn't plan to find. I stop at information centers entering each state, collect travel guides and talk to the volunteer hosts. I also stop at travel information centers for interesting towns and small cities, the folks who work at those often know a lot about what there is to see and do in their area, and they volunteer for these jobs because they like talking to people. Stuff I collect at these places also fills my travel file boxes.
Road tripping in a RV is not much different from road tripping in a car. Your days will be somewhat shorter, because you will usually want to get stopped for the night before it is dark, and you have setting up time, and camp breaking time in the morning. When my wife was still alive, she usually liked to check the campground directory early afternoon for places we could be in the evening, make reservations or at least make sure there is space (liked to do the same for hotels). I'm now more willing to sleep in a parking lot, many RVers do that regularly.
Connecting with people to travel together? I'm not sure how, and don't particularly like caravaning, I find I am too different from a lot of people about what I find interesting and my pace for seeing it. I'll wait several days for the right light and weather for a photograph, not everbody will tolerate this. If you absolutely do not like traveling by yourselves, there are several companies who still arrange and lead RV caravan tours, but joining one can be pretty expensive, and you no longer have choices about what you will see, nor about the pace at which you see it; like getting on a bus tour, except you have to drive.
That's all about road-tripping. Maybe you are not thinking about road-tripping, maybe you want to move around but live in different places for a while, a few weeks to a few months? Then you'll be looking for places that are at the center of a larger collection of interesting sites and activities, like maybe Moab on the Colorado Plateau, or Durango in the western Rockies, Yellowstone-Teton Mountains in NW Wyoming. For that sort of travel, you will need a more firm schedule, so you can make reservations for longer term stays, more like what snowbirds do. I have not much experience there, by RV, since my longer stays tend to be at peoples' homes.
Tom Test
Itasca Spirit 29B
