I'd go with the FS. It's at the end of Washington Avenue, which is the downtown loft district with many bars/restaurants/etc, to check out after hours. The casino it's attached to also has a number of decent restaurants and some other things to do.

Yes, it's a "so-so" area, I guess. Lumiere and the FS are right on top of Laclede's Landing, the go-to spot for 18-25 year olds to go out drinking on the weekends. There is also a good sports bar (Skybox) and a decent sushi place (Drunken Fish) on the landing.

The area directly west of the hotel is, of course, the lovely I-70 highway, BLECH. Past that is the Edward Jones Dome, where the Rams attend games (but they don't play, obviously), and the beginnings of downtown.

The metro is, as stated above, just a hop and skip from either hotel. From the airport - downtown it's roughly 33 minutes, as that's a lot of stops and about 15 miles away. I'd always recommend metrolink from the airport to the area, unless you're married to the idea of having a car. A car would only be necessary if you want to venture away from downtown for dinners or drinks, which I would recommend at least once while you're in town.

If you want any recommendations for evening/weekend things to do or see in St. Louis, feel free to PM me. I'm a huge booster and fan of St. Louis. The least you can do is come to Lafayette Square and eat at one of our many fine restaurants.