St. Louis in April
If you want memorable, I second Niche on Sydney Street (Brasserie, not so much). The food is elegant and edgy. Also around the corner is Sydney Street Cafe -- a tad more traditional, but just as excellent. Bring your $$ for both, but difinitely worth it. Make reservations and you need to take a cab.
Sydney Street Cafe
2000 Sidney St, St Louis, MO 63118
and then a coupla gin buckets on the patio at Venice Cafe (hey you're cabbing after all) just a few blocks from there really. Venice opens at 5 so a before dinner drink would work too (gotta check out the mosaics in the bathrooms or the Explorers Club upstairs (do they still feed the Oscars at a dollar a pop?)
If you want to try an "old school" treat, check out Al's. Short cab ride from the arch. It has been on the riverfront since 1925. I don't believe they have a menu persay., They bring this huge platter out with all the different cuts of things. They present 3 or 4 options for all but will basically do whatever you want.
Neat place for a piece of history.
The great old-line restaurant there is Tony's. Italian but super-luxe, sort of ultimate comfort food. The great secret is that if you want it and it's not on the menu, if they have it, they'll make it for you. A very serious restaurant used to major celebrations, proposals, visiting celebs, etc., family-owned and operated. (A very nice family, BTW.)
Soups are great, many of the other first courses also hard to choose among (? scallops?), the classic favorite entree is lobster Albanello, in a creamy sauce that needs to have some plain pasta to go with it, IMHO. And I do think their chocolate cake with homemade banana ice cream is the dessert of choice. Fine wine list.
If you are needing modern American, call Niche for a reservation and then take a cab. French bistro would be Brasserie by Niche, ditto the res and cab. Both of them are more casual.
1831 Sidney Street, St. Louis, MO 63104
410 Market St, Saint Louis, MO 63102
Brasserie by Niche
4580 Laclede Ave, St. Louis, MO 63108