Rented from National in COS a few times. Here are my last 3 or so rentals:
Chevy Malibu (Stripped Down)
Ford Fusion Titanium (Fully loaded!! And New)
Toyota Camry (Decent options but smoked in and smelled gross)
Lexus CT200H (For being a Lexus, it didn't have many options at all)
I would love to have an Emerald Aisle here!! They have the space for it.
As far as any air travel, I always go COS due to short security lines and easy access to terminal from parking lot.