The Intermediate SUV class is actually a pretty good bet, because it includes two Subarus (Outback and Forester) that only come in AWD. I've seen a lot of Outbacks in various Select-and-Go sections, and if you call ahead 24 hours and request a Subaru, you've got a pretty good shot.

Most of the other SUVs come in both 2WD and AWD configurations, so if you get an Escape, Compass, or whatever, you'll want to check the configuration. My experience is that it's usually obvious on the vehicle itself, but the agent in the booth will have no idea how your assigned vehicle is configured (it's in their system, but hidden way down deep).