We- wife, me and one or two biggish dogs(greyhounds) travel in out 1998 Suburban.
Two adult humans+ 1 or two dogs sleep in the back at rest stops on a double mattress-a double mattress - floppy futon mattress fits just fine in the back of a Suburban with the second row flat and 3rd removed.
It is almost like sleeping on the bed at home- except we don't sleep with the dog on the bed at home.
Arty- the dog- would be up for sleeping in the bed at home, but I don't need a bad breath dog hogging the bed at home!!

My point-I have eyeballed vans- they are pretty tempting for the comfort, but the Suburban is pretty comfortable on long trips,and in general it is easier to find a good Suburban than a good van.
Also- 1996-1998 Suburbans are pretty cheap around here-maybe $2500-$3500 max!!

You will do alright either way- but the Suburbans are pretty good travel vehicles-get good mpg also- 19-20 mpg at 65 mph-
Dogs love the Suburban- sure they would love the van also.