Actually the "hottest" restaurant in STL right now has not been mentioned as of yet -- Red Moon (Red Moon Website). It's an Asian fusion (aka Pan-Asian) restaurant located just off of Washington Avenue downtown. It has actually been listed on national lists of "up and coming" restaurants.

Other suggestions...

Sqwires (mentioned earlier) is located in the Lafayette Square neighborhood. Neat building, great food. (Sqwire's Website)

1111 Mississippi is in the same area. Italian influenced. (1111 Mississippi's Website)

Lucas Park Grille is in the downtown/Washington Avenue district. (Lucas Park Grille's Website)

Sidney Street Cafe is in the Benton Park neighborhood. It's one of those restaurants that qualifies as an undiscovered (to most) gem. Call early for reservations! (Sidney Street Cafe's Website)

Greg