I'm also in favor of the 48" plastic crate. My dogs sleep in the plastic crate (door's always open) all the time but they rarely used the wire one. I actually have to kick DH's dog out of it to lock up the pup if I have to leave, lol.
My other issue is that some of the wire crates are just oversized small animal cages. I mean, totally useless and way too flimsy for a dog, lol. I bought my plastic crate second-hand from an ad I found online, so it didn't break the bank.