Paul's Famous Hotdogs and Britt's
I imagine you'll probably take I-40 to Wilmington. Get off at Rocky Point, NC-210, and stop at Paul's. They have a place right by the exit or, even better, drive the few miles to the original. You will love their hotdogs. They've been serving them since 1928 and have been a stop for most people driving to Carolina Beach. Their famous relish sauce (created because of WWII meat rationing) is something else.
See the Battleship North Carolina in Wilmington, then drive to Carolina Beach. Check out the old boardwalk and get some melt-in-your-mouth Britt's Donuts. It will be worth your stop. However, eat them there, they don't taste all that great if you take some to go.
Farther south on US-421 is Fort Fisher, the site of one of the largest forts ever built on US soil. The fall of this fort in January 1865 effectively sealed the fate of the Confederacy.
Continue on down to the Fort Fisher-Southport ferry and take a free ride across the Cape Fear River. Check ahead for schedule. There will also be schedules posted along the highway.
Right on the NC-SC border is Calabash. They have some of the most unique and best shrimp you'll ever get. Calabash shrimp. now that's something.
See the historical Pavillion in Myrtle Beach before they tear it down.
Just some ideas.
Keep on Down that Two Lane Highway. --RoadDog