By the river there is a mile or so of graffiti that's quite impressive. The Venice Cafe is very eclectic and fun.

I've lived there in the past, and still have friends up there. Personal opinions of things to look into possibly seeing.

-The Arch, (duh!)
-The City Museum (more like an amusement park) --The Magic House
-Science Center,

Those are almost MUST DO'S if you have kids, or are a bit of a kid yourself. I'm not even going to describe The City Museum... there are youtube videos of people showing their fave parts. (The multi story slides are hilarious and worth it!)

-Grants Farm... lots to do, not outrageous. There is a special Clydesdale experience tour you can do.
-LAUMEIER SCULPTURE PARK is cool.
-The Transportation Museum (if you're into trains!)...
-Budweiser Factory (free tour! Beer at the end!)
-The St.Louis Zoo (free admission I'm pretty sure!)
-'The Hill' for outstanding Italian food! Just google Italian Restaraunt the Hill and you pretty much can't go wrong. Charlie Gitto's!
-Boeing has a cool area to tour. Lots of aerospace stuff from all the companies they are made up of.
-Purina Mills has a cool tour setup!
-the Old Court House (near the Arch) where the Dred Scott case was heard. Very interesting. Went last year for the first time.
-The St. Louis.Cathedral is pretty impressive. I think its the largest collection of mosiac artwork in the world. Went there last year for the first time as well. It is impressive.
-Lafayette Park Victorian Gardens...
-The Jewel Box
-Soulard Farmers Market- Opened in 1789.
-there is a new Blues (music) museum. I have not been, but want to go.

Google St Louis cemetary tours! It is crazy how many "Oh damn! I remember him/her!" Famous people from history were buried in the two Cemeteries. (They are right by each other)

-Jefferson Barracks. Not as famous as Arlington Cemetary, bit it is amazing, and lots of history.

Ted Drewes Frozen Custard!!! Definitely do this after dinner!!! I'm not kidding.

A short drive over to Alton Illinois and you can get a hilarious picture of yourself standing next to a lifesize statue of Robert Wadlow, the Alton Giant
(Not my picture... just grabbed it off google images! But you get it!)

And do yourself a favor and go to Crown Candy Kitchen for lunch while there, and order the BLT. They don't call it the heartstopper without reason!
I never went when I lived there but try to hit it every time I get up there on a visit!!!

Definitely try Couchsurfing.

It will be a grand excursion Are you an adventuresome road tripper, or the type of traveler who wants to get from point A to point B as quickly as possible?

According to Google maps, if you take the route through Iowa on the west side of the Mississippi River, it will take around nine hours. If you take the route through Illinois it will take about one-half hour longer, and you will go right through Springfield

Maybe you could take one route to St. Louis and the other one on the way home. I am sure that the Iowa route is much more scenic and probably the most notable stopping point is Hannibal Missouri.

On the Illinois route, you will be running parallel to Route 66 from just south of Joliet, Illinois through Springfield all the way to St. Louis. Springfield, of course, has some wonderful Abraham Lincoln historical sites as well as geocaching opportunities. There are at least a couple of other agnostic.com members from Springfield who are very active on the website.

Nooh, but if you happen to be passing by Mojacar.........