The roads around Yosemite National Park are challenging and have great views. I was there in spring when the snowmelt makes the transient waterfalls.
I like A1A Miami FL to Key West, not a road for curves, but when you go over the bridges on a good day, and it's the Atlantic Ocean on one side, and the Gulf of Mexico on the other, the scenery is spectacular. it's almost like you're flying-low. If you're used the riding along the Great Lakes shorelines, and then you make this ride, it gives you a 'whole 'nother perspective on large bodies of water. The blue waters of FL make the slate-color of the Great Lakes water look plain and uninviting. And if you stop at John Pennekamp Park and do some snorkeling, the schools of fish, the corals, and other marine life will make it a trip you won't forget for a long-while. Ceviche and conch chowder are good foods to sample and try the Keys-equivalent of hush-puppies, conch fritters.