Didn't read through this whole thread, sorry, but I wanted to chime in because I'm actually currently on a road trip with my dogs.
The trip is 15 hours, from my house to my parents', and I've done it 5 Christmases in a row now. Luna's come with me every year, and Keegan's come too these last two years.
I love traveling with my dogs, it's definately better than going by yourself. As far as safety, that's definately something I'm always concerned about, as a young, single woman driving through sometimes questionably safe areas. But I actually feel a little safer with my dogs in the car. Even though I have a chihuahua and a collie, two breeds who aren't generally thought of as dangerous, they do act as a deterrent (I think) and I feel safer with them with me.
I stop and let them out every 2-3 hours (it tends to coincide with gas or meal breaks), they usually just toilet in grassy areas at our stops. Luna's perfectly comfortable sleeping in the car, and Keegan's still improving; so for the most part they just sleep the whole ride unless we stop and take a break. They're usually a little wound up when we get to our destination, so I have to be ready to let them out to exercise pretty much before I even say hello to my family.
I've only flown with a dog once, with Keegan when he was a baby and small enough to fit in the cabin under the seat.
That was actually VERY stressful..... I find flying stressful in the first place, but when I have to take care of a dog as well as myself, well, it was hard. I think, though, that dogs are allowed out of their carriers in the airport.... They have to be inside until you get through security, and of course the whole time you're on the plane, but while you're in the terminal I'm pretty sure you can have them out. I didn't when I flew with Keegan, because I was rushing to get to my gate and didn't have time; but I did let him out when we got to baggage claim.
