Like many in this thread, I like to drive when I feel that sense of adventure creep up on me. If I finish work or school early, and the sun is out, I just can't help but turn left when my rout home would normally require a right. From there on, who knows. The GPS goes in the glove box and I take the roads I've not yet driven.
One time, on the way home from the mall, I went the wrong way by complete accident. When I realized this, I ended up thinking, "Screw it, you've never been this way before." 40 Minutes later I was at a gas station across the road from a rural(ish) drag strip, and though I'm not really a fan of that sort of thing, it was great to slurp down a Coke and watch the various kinds of competitor cars roll in and out (I couldn't see the actual strip from the gas station).
I'm also in the no A/C group--I much prefer to feel the wind, and hear the car in a way that only works with all the windows down, even on the highway (unless it's a really long trip).
The other must is trees. Or corn fields. Or something that isn't that omnipresent background of melancholy concrete and outdated buildings right around my neighborhood. Usually this means areas in and around parks/nature preserves, or out in the more farm-ey parts.