I just wanted to really, really, REALLY emphasize to do a TEST RUN before the actual move. That includes testing them in the car, in the carriers, with gravol, with sedatives, EVERYTHING.
I first learned this lesson years ago, moving just 6 hours with my kitty. We got a sedative from the vet, popped the pill, put him in a carrier (the mesh bag type), and carried him on my lap (I was in the passenger seat). He was freaking out the whole time. As in, foaming at the mouth freaking out. Then at a rest stop, we went into a diner for some lunch, leaving the window open a crack so the car wouldn't overheat. When we got back, he was GONE.
He had managed to force the carrier open and squeeze out the less-than-2" window opening. This highway diner was surrounded by dense woods all around. He was gone.
Fortunately, he was wearing a harness and leash. After about a half-hour of searching (and me nearly collapsed from grief, shock, and guilt), a dear dear friend I was travelling with (and all the dearer after this) FOUND HIM, the leash wrapped and tangled around a tree. He got a nasty scratch all up his arm for his trouble. We chalk the whole thing up to a bad reaction with the drugs.
Lesson learned -- here's the next experience:
We moved last summer with our two cats, 16 hour drive (no hotels, all in one go). In preparation, we talked with our vet who suggested the children's gravol first, before trying the 'real' sedative.
First test run, half-hour to one-hour drive with each cat individually, in the carrier, no meds of any kind. One cat was just kind of pissed (the one we thought would freak out), and the other one FREAKED OUT (the one we thought would be fine lol). I don't just mean panting and meowing, I mean FREAKING OUT as in he was going to hurt himself.
So we tried the gravol. Test runs: Pissed cat -- no difference. Freaking out cat -- still freaking out, except yowls sounded in pain, then he PROJECTILE VOMITED all over the car. Yup.
So we tried the sedatives. These aren't complete knock-you-out drugs, they just make the cat kind of loopy. Tried them with a minimum dose. Poor things, it was actually quite funny -- their inner eyelids were half-closed and they couldn't stand up straight or walk around. It was like they were "tripping". They still weren't HAPPY in the test runs, but freak-out cat no longer freaked out. It was more like "wow, man, this house is moving... duuuuude..." Drugs wore off within the predicted time parameters with no side effects.
So at move-time, they were pilled about a half-hour or hour before we set out, to give it time to take effect, and they were re-dosed once during the trip. They had almost no interest in food or water, or in peeing. Or in being let out of their carriers. We'll just stay in here and be miserable, thank you very much.
They were a bit mad at us for a couple days after arriving, but quickly adapted to their new home and we're SO glad we went through the trouble. It went smoothly, because of the test runs!!! I can't imagine the projectile vomit halfway into a full-day trip lol...
Edited to add -- we also did something similar to the above poster. I actually flew by plane with our toddler, rather than subject her to the long drive, and DH drove flat-out in one long stretch (just stopping for pee breaks) with my 10yo son. This was better than being completely by himself with angry cats, my son could help keep an eye on them, make sure they were okay, etc, while DH focused on driving. We did look into flying the cats too, but there are ever-changing regulations and lots of dangers and stress, this actually seemed the least-stressful-to-the-cats method of transport.
