Family trips we've done, either my family of four, or the family of 6-10 (it grew over 18 year span) I grew up in.
Mount Rushmore-Glacier-Yellowstone (from SE Michigan, three weeks).
Loop of Michigan L.P. lakeshore (Huron and Michigan) parks and communities (one week from SE Michigan).
Michigan U.P.: Mackinac Island, the falls at Newberry, Sault Ste Marie and Superior shore to Wisconsin, returning through Wisconsin, done from SE Michigan and from NE Oklahoma.
Historic communities and settlements of Iowa and southern Wisconsin (sort of a "Little House" and Amana tour, leading to Baraboo and the Wisconsin Dells.
San Antonio, stays of one to two weeks, visiting Hill Country towns.
Grand Canyon and west-central Arizona attractions like Sedona and Jerome, with some time in Phoenix, then Carlsbad Caverns on the way back.
National Parks and monuments of Colorado Plateau: Arches, Canyonlands, Colorado NM, mesa Verde, Bryce, Zion, Escalante, and Monument Valley (you kind of have to at least go through it).
Monticello, Richmond, Williamsburg and Jamestown.
Most of these places lack theme parks, if that's what you are looking for (we are the generation before Disney, Dollywood and Legoland). But many of the historical places are re-enactment settings, which my girls and grandkids found interesting starting at about age 8-10.
Otherwise, most of it is visiting historical places, seeing special scenery or geology, and outdoor activities. Some of it was just about the camping, when we were camping and not just RV traveling.
Tom Test
Itasca Spirit 29B