I haven't done a "road trip around the U.S.", per se. But with my family we did have a couple two-week vacations where we hit up a bunch of places. Once we went and visited various cities and places of interest in Maine, Vermont, New Hampshire, New York, Connecticut, Massachusetts, Pennsylvania, and Maryland. Another time we went West and visited Texas, New Mexico, Nevada, Arizona, Utah, Wyoming, South Dakota, Minnesota, Wisconsin, and Illinois.
The states I have never been in at any point are Alaska, Hawaii, Oregon, Washington, Idaho, Montana, and Rhode Island.