For most concerts and theatrical performances, you can buy tickets from the venue’s box office (kassa), the many theater-ticket kiosks (teatralnaya kassa) around the city, or from the central box office at Nevsky Prospekt 42 - but for ballet or opera at the Mariinskiy Theater you have to depend on the tourist service bureau at the largest hotels, which will add a surcharge or use the Mariinskiy website (http://www.mariinsky.ru).
You should definitely try to hear some Russian Orthodox Church music, which is solely choral and wonderfully in keeping with the rituals of the faith. Splendid choirs perform at the Preobrazhenskiy Church near Liteyniy prospect (daily at 10am & 6pm) and the Alexander Nevsky Trinity Cathedral (6pm daily except Wed). The choir at the former is composed of professional singers from the Capella Choir. Orthodox services are also held at the St. Nicholas Cathedral at 6pm, and at other churches on a less regular basis. The best services are those on Saturday evening and Sunday morning.
St. Petersburg has dozens of private galleries and exhibition halls, in addition to the temporary displays which can be seen in its museums and state galleries. Most of the private galleries cater for the tourist market and are packed to the rafters with picture-postcard paintings of the city alongside matryoshkas, balalaikas and other folk objects. However, if you search hard enough there is some fairly decent art on display, too, while at the city’s best-known exhibition spaces you’re guaranteed to find something interesting at most times of the year - look out especially for temporary exhibitions at the Benois Wing of the Russian Museum, in the Engineer’s Castle. In addition, there are countless street artists showing off their talents along Nevsky Prospekt and outside the major tourist attractions.