I don't like driving/riding in the car for very long anymore--my parents and I generally stop every 1.5 to 2 hours to stretch our legs a little, use the bathroom, etc., and about 4 to 6 hours is the limit we're willing to drive in a day, like as part of a longer vacation trip when we're going to spend the night somewhere.
At Christmas we have to go visit extended family and it's a LONG 2-hour drive from our house to theirs. We might stay 3, maybe 4 hours max, then turn around and drive back home. It doesn't help that to me at least, I'm not really keen on going and it feels more like an obligation than a want.
I think that if I ever had the opportunity to move to another town, 2 hours would be the upper limit I would want to be away from my parents, unless I was able to have them spend the night. I.e., 4 hours round-trip would be the max I would ask them to do for a daytrip, and I would expect we would spend at least 4 hours and preferably more together. Right now they live about 30min away and can easily come see me for a few hours or even just a meal.
On the other hand, my friend Amy and her DH do the thing where you get up at the crack of dawn and drive for 10 to 12 hours with only carefully planned and timed stops, stay overnight, then get up and do it again to get to the next place on the route. They have family 20 to 25 hours away that they visit a couple times a year this way. Amy feels it's more cost-effective to drive than to fly and she tries to make the car trips more fun with music, food, etc., but the primary goal is to get from A to B, not to have a road trip. I just couldn't do it.