Zoo’s a good bet. It’s free, and could take up half a day at least, maybe more. If you get there early enough to park on the road nearby, you can park for free. Otherwise there are parking lots just across from the entrance that charge a little.
I second the City Museum. Easily you could spend three quarters if not a whole day here. It’s something like 10-12 bucks per head, but man, it’s worth it. I’ve never seen anything like it anywhere. link
The Arch is interesting, though they’ll likely be bored by the museum underneath (unless they’re particularly interested in Expansion-era history). The ride to the top and the view is interesting, but a little expensive. It is the tallest national monument though.
Fitz’s is good stuff. The food’s good too, if a little pricey. I don’t know if they’re currently bottling or not (there’s a big glass window where you can see into the factory part from the dining room). It’s way out in University City though, so if you’re not driving and you don’t want to take the bus, it probably won’t work out. link
Crown Candy Kitchen is in a bad part of town (but maybe close enough for the shuttle), but the food is good and relatively cheap and the malts are amazing. link
Hmm.
I can’t really think of much other fun “kid stuff” to do besides take in a ballgame if they’re into baseball (afternoon game on Wednesday with the Rockies). Maybe see the park anyway, if there’s interest.
I’d say if the baseball thing works, there’s most of Wednesday right there. Then the Zoo/Science Center (they’re both in Forest Park) on Thursday and City Museum on Friday – and there’s your week. The Arch could go with either the game or the City Museum. If no baseball, I’d suggest doing the Arch on its own, and then maybe walking down around the River and Laclede’s Landing.
As far as food goes… There’s the aforementioned Candy Kitchen that has sandwiches/lunch-type foods. Fitz’s that’s sort of far away. There’s a bar/restaurant downtown called Calico’s that’s decent (don’t know how kid-friendly though). If you want to try St. Louis-style pizza, I’d go with that or Imo’s. If you want the best pizza anywhere ever (not St. Louis style), it’s to be found on the South Side. Delicious. Most of the places I would recommend are likely too far away for a shuttle.
Here’s the weather, by the way. The zoo has some indoor areas (Penguin house, monkey house, reptile/amphibian house) so I wouldn’t worry too much about that. One of the City Museum’s biggest features is a humongous climb-all-over … chunk of sculpture and metal and junk. It’s outside, so try to go when it’s not raining…if it is you can look at the stuff inside (There’s a lot inside too) and try to wait it out.
I’m not originally from St. Louis, but I’m from nearby originally and have lived there for about the past six months. Any more specific questions, feel free to ask and I’ll see what I can do.