I've rented several times for ski trips in DEN. Here's my unorthodox suggestion. Rent a couple of different SUVs & pick the one that best suits you when you get there. The reason I'm saying to rent 2 or 3 different ones is because if you decide you want to upgrade, they charge you WAY more to upgrade on the spot than it would had you just rented the larger car to begin with. I'm a Pres Circle member with Hertz & I've been screwed by that stupid policy (as upgrades don't apply to SUVs for PC members).

There's no cancel penalty if you choose not to rent a car & you never give them your CC in advance for reservations.

Just my 2 cents...