We will travel about 10 hours and our cat freaks out on the road. One told me to give her benadryl to calm her and make her sleep.

DO NOT give your cat anything without your vets say so, give them a call explain and they will either recommend or perscribe do this properly don't give a cat something that could well kill it.

My cats are not the best travelers... they tend to howl, alternatingly, in stereo. I was dreading the trip from Los Angeles to Austin because of it. But really, there's only so much they can do before they tire themselves out.

What I did was get a wire cage (per cat) big enough to hold a small litter box, still have some clear floor space, and made a hammock out of some scrap cloth and pvc pipe for half of the space. So essentially they had the "downstairs" and then a second story about a third of the size of the cage. Put a towel on the lower level, outside the litter box. And eventually, once they got through making their dislike of the whole idea apparent, they just curled up for the rest of the trip. With an occasional complaint session, especially after stopping for gas/food, etc. But they had enough space to move around, the litter box for those needs, and I put food and water in the first day, but they wouldn't eat, so just water the second day. It helps if you have a second person, and put the cages somewhere where they can reach and do a scritchel through the cage wire while you drive.