First, understand that Americans will define things differently depending on what part of the US they're from. There's an old joke that Americans consider 200 years a long time and Europeans consider 200 miles a long distance. That's true inside the United States too.

Some parts of the United States are more spread out than others, so people there are more used to driving longer distances. The central US is very spread out. The Northeast coast of the US, on the other hand, is relatively densely populated, so major cities are closer together. The Southeast coast gets a bit more spread out but not as spread out as the central US. And so forth.

Day trip, 2-3 hours drive each way: A day trip is, by definition, a drive that you can drive there, do whatever, then drive back, in one day. Typically 2-3 hours drive each way is what people around here (Pennsylvania, Northeast US) would consider a normal day trip.

When I was younger and had more energy, my brothers and I might drive as much as 4-5 hours each way for a day trip. These days, I could do it if I had to, but I wouldn't enjoy it.

Short vacations, 4-6 hours drive each way: For visiting relatives and friends for holidays, where I'm usually planning to drive down on day one, spend a day or two there, then drive back on the third or fourth day, I routinely drive up to 6 hours.

Long vacations, a week or more, up to 10 hours max but I'm older and now I'd think about flying instead: I did a 17 hour drive (Pittsburgh, PA to New Orleans, Louisiana) seven times for long visits, starting in my late 20s and ending in my late 30s. Towards the end of that, as I got older, I found that I really needed to rest the day after the drive.

A lot of the physical stress from long drives is simply having to sit in the same position for several hours. If you stop every 2 hours or so and get out of the car, stretch a little and walk around for 15 minutes or so, it makes long drives a lot easier, even when you're young. When you get older it matters a lot more.

Similarly, I did some very long trips using a van. Just being able to move around a little inside the van made the trip a lot easier, physically.

Of course, for all of that you have to factor in fuel costs versus the cost of a plane flight. Gasoline (benzine to the Dutch) costs a lot more today than it did the first time I drove 17 hours. Even 5 or 10 years ago, the fuel versus flight tradeoff was close.

Although of course, if you fly, you don't have a vehicle to get around your destination, and public transportation in the US generally sucks, compared to Europe. So you'd either have to count on friends or family, or rent a car.