St. Louis is easy to get around compared to larger cities. That said, this location is great because it puts you on the central highway leading to the financial centers of downtown and Clayton. If you want to attend sporting events downtown it should take you no more than 30 minutes to get there. The downside with this location is that you have to drive to everything, but unless you're staying downtown that will generally always be the case in St. Louis.
As for the property, my wife and I both thought the staff was very friendly. The breakfast is great with a waffle and omelet station as well as a good variety of other warm and cold foods. The room was comfortable and quiet. We didn't get to use it, but they have a well-equipped exercise room. Overall this was a very pleasant Marriott stay and we will be sure to return. Very clean as well.