Alphonse Mucha, one of the most famous artists of the Art Deco period hailed from Prague, and his influence remains visible all over the city. The Smetana Hall is an exquisite architectural example of the decadence of Deco. Even if you don't get tickets to the symphony, it's worth it to explore the building and marvel at the architecture. There's even a little shop inside with beautiful replica (and some real) Art Deco jewelry.
Mucha's legacy can also be seen in several of the beautiful stained glass windows at the Castle, and in numerous signs and advertisements around the city as well. Every bookstore and souvenir shop has magnets, postcards, and art books featuring Mucha's work, if you want to take an Art Deco memory home with you.
I suggest tossing out the map and getting lost in the streets around old town and seeing what Art Deco surprises you can find. It worked for me.