Depends on who you rent with. My company the Ford Edge, Ford Flex, Hyundai Santa Fe, Suzuki Grand Vitara, and Honda CR-V in AWD. All our pickups are 4x4 as well. I think our Ford Tauruses are AWD too. Mind you we only operate in Canada. Most rental agencies in snowy areas should stock AWD vehicles. Call and ask them. They usually won't guarantee a specific vehicle (only goes by size/class) but they'll try to find your preference.
Like the others said, the key to winter driving is just to take things slow. I've driven nearly everything under the sun in snowy conditions and that's the most important piece of advice I can give.
Don't make sudden movements, plan your stops, turn into the skid if it's FWD, do the opposite if its RWD. Your car will tell you if it's starting to loose grip. You'll be able to feel it. Weigh down the rear in RWD vehicles. Drive slowly in snowy conditions. Plan your trips and give yourself plenty of time. If you do get stuck, rock your car. Cycle between 2nd and reverse and gently ease it out. Use a low gear on icy roads. 2nd is good.
Another good thing to do is pack yourself a winter kit. Bring with you a portable tire pump, blankets, flashlights/flares, ice scraper and brush, jumper cables, some water and food, lock de-icer, cell phone, and a small shovel. I've only gotten stuck in the snow once but I'm sure glad I had a kiddie shovel to dig my wheels out.
Rental companies should offer roadside assistance too, just in case you do get stuck.