I have rented FWD on nearly all of my trips due to the obnoxious premium cost of AWD. It depends upon specific location and whether you have to climb/descend steep hills. I've had only 2 drives into the Bozeman/Big Sky region, and the area around West Yellowstone seemed to collect the most snow on the road. The roads in that area were decent enough and not a problem driving on a packed powder surface. I'll defer to local comments about the canyon between Bozeman and Big Sky; it does have a reputation, reminds me of the Walker River canyon on 395 near the CA/NV border which can be difficult in snow.