There are two excellent menswear stores in St. Louis:
9831 Clayton Rd
Saint Louis, MO 63124
Zegna, Vestimenta, Etro, Samuelson. This place has the best deals during sale time.
265 Plaza Frontenac
St Louis, MO 63131
Brioni, Canali, Ravazzoli
Neiman Marcus and Saks Fifth Avenue always disappoint me, but they're both at Frontenac Plaza.