This is a combined road trip of nostalgia and an eagerness to discover more.
Gambier, Ohio, United States
I spent three (academic) years here as an undergraduate at Kenyon College. There are not a lot of "touristy" things to see - but a lot of nostalgia. This would be an idyllic place to start (or end) a road trip - it was the beginning of many road trips in my 20s.
Rehoboth is a wonderful beach town. It's small enough to be small-town, but big enough to be interesting. There are plenty of restaurants for the gourmand or frugal eater, plenty of beach space, and a charming boardwalk for the kids.
It can be a bit on the crowded side for those who prefer a quieter beach - but there's also North Shores.
There are also some interesting road trips to take from Rehoboth, like to the Dogfish Head brewery in Milton (about 15-20 minutes away).
South Beach, Florida, United States
Ah, South Beach.
Yes, it's definitely a "party town" - but it's also fine for non partiers. There are museums and restaurants a-plenty. The beaches are, of course, gorgeous. A big-city beach for sure (especially compared to Rehoboth), but a relaxing launching pad to explore Miami and the rest of South Florida (the Keys, the Everglades, etc.).
Probably a polar opposite from South Beach. I've only been here twice, but both times it left an indelible impression and a desire to come back. Low-key island life at its best.
It is certainly touristy, though. I'm sure that there are more "relaxing" beaches to be found on the other Keys, but the charm of Key West can't be understated.
I've only been here once - spring break when I was 18 - but it left me wanting more. Of course I had begniets and explored the French Quarter. It was, in fact, on another road trip through the South - driving down from Little Rock (we stopped in Vicksburg and Macomb, Mississippi - both also charming towns).
I've always wanted to go back.
There are so many places left to see in the US. These are a few of my favorites in the East - I could do a whole other list on the west.