Great historical theatre of Saint Petersburg. The ...

Great historical theatre of Saint Petersburg. The interior of the main hall is very impressive, and is interesting by itself, with the Czar's balcony and architecture.

Note that when buying a cheaper ticket the seat you'll have will probably be on the third floor, where the seating is simply a long wooden bench, with a back rest. Not that comfortable, especially when you are supposed to sit there for 2 hours, and disappointing when even the cheapest ticket is not that cheap. When sitting in the back rows of the third floor your field of view of the stage will be limited as well, and most likely people around you will not follow a common sense theatre etiquette - some will talk, some in front of you will take pictures using their phone, essentially blocking your already limited field of view and distracting you. Some people even took pictures using their flash, which was way beyond reasonable by any means.
TL;DR: Avoid third floor at all costs, no discount will justify such ruined theater experience.