Location, location, location
If you're arriving in St. Louis by plane, you may wish to pick up your rental car from one of the many car rental companies at the airport. Alamo, Avis, Budget, Dollar, Enterprise, Hertz, National, and Thrifty all have registration counters in Lambert, St. Louis International Airport (STL). Payless' pick-up counter is only a shuttle ride away. Expedia can also show you a map of the nearest car rental locations to your hotel and the rental cars they carry. (And keep in mind that off-airport car rentals are often cheaper than at the airport, even from the same car rental company.)
Picking the rental car that's right for you
Expedia's Total Pricing
Unlike some other online travel sites that show you a cheap discount rate for your car rental when you're shopping and then heap on taxes and fees when it comes time to pay, Expedia shows you the final price up front. What you see is what you pay.
*Advantage Rent-A-Car, Dollar Rent A Car, Enterprise, Hertz, and Thrifty