I grew up just down the hill from highway 84 in California, and used to know nearly every curve on the road by heart. I'm still close, but don't drive it as much as when I was a teen.
I've ridden the PCH (Highway 1) from Carmel to San Simeon (Heart Castle) on my bicycle (and I've driven it). It's about as good a century as there is, I think.
Memorable drives for me: Sarasota, FL, to San Francisco, via Madison, with my sister when we were both coming home one summer.
Denver to Madison in a day--my last speeding ticket. When I crossed the Wisconsin river, and saw it was 80 miles to Madison, I thought, "I can be there in an hour!" Police didn't think that was a good idea. 1000 miles in a day by yourself is probably also not a good idea.
Drove San Francisco to D.C. with a girlfriend in college. Best part was through the Smokey Mountains. Alas, Dolly World was closed. /sarcasm (but true story).
San Francisco to D.C., through El Paso, with a great friend when we graduated college was pretty awesome. Didn't have enough time to really see the sights, but it was a great drive. On the way back to El Paso, saw fireworks over Little Rock as I drove into town. That was memorable.
I drove from California to El Paso and back a few times. While it was a bit drab in parts, other parts of the desert were spellbinding.
I used to drive from Tennessee to Chicago to visit college buddies pretty often on Highway 41 (with the Allman Brothers cranked up)--once or twice I took the interstate (57).
In college, drove from Madison to D.C., through State College, then stopped to watch the Badgers upset the Nittany Lions on the way back. That was pretty cool.
I-80 is pretty boring through most of the midwest. The stretch from Salt Lake to Reno is brutal.
SFIrish and I drove from San Francisco to Salt Lake, then up through Idaho to Helena, MT, and Glacier, then west through Couer D'Alene to Seattle, then Portland, the redwood forests on the California coast, and back to San Francisco. That was a pretty cool trip. Nearly cooked our brakes coming from Tahoe down to Reno on back roads, nearly ran out of water backpacking in Idaho because the rivers were intermittent (not shown on map), nearly got caught in a wildfire in Glacier while backpacking (when we came back to our truck, there was a note asking us to check in with the ranger on our way out, and in the parking lot were only fire vehicles; when we got to the ranger station, they told us we were literally the last people out--we had been blissfully ignorant). Went to the other side of the park, but could only go halfway on Going to the Sun because of the fires.
Nearly got caught in a tornado in Texas on my way from Houston to Centerville. Had some realizations about the importance (or lack thereof) of work that day.
