You can get a ski rack added to any rental. If you decide not to add the rack make sure they don't see your skis. They don't like that stuff in the car with the seats down and will force you to get the rack. It's honestly easier with the rack anyways.

I would go for the cheaper.

Don't let them trick you with a "you need a big suv in the mountains". I drive I-70 every weekend in the economy offering. If the roads are open then you can get up there in an of the vehicles, except I don't like the mini vans one bit. You could even consider a midsize car instead of an SUV. Be sure to use the gears going down the passes instead of just laying on the brake. It is a rental after all.

Simon