the Metro-link is your ticket to explore town, the Arch is a must, the zoo is good, there is some good eatin on " The Hill ", The Lewis and Clark frontier park is cool in St Charles, and do not miss Cahokia Mounds what ever you do, got a good race track also " Gateway Motorsports "
Never stayed at the Casino Queen but I have left my car there and got on the metro, I guess it would be safer that a place without a guard.
as already said, rush hour is a killer, before and after not bad at all for a city that big, Atlanta is 10x worse.