There is in Russia this chain of shopping centres called Mega, and the biggest one in SPb is the Mega Dybenko. It is located in the crossing of Murmanskoye soshe and the KAD (the circle road). You can easily get there by free bus from the metro stations Lomonosovskaya or Ulitsa Dybenko.
The shopping center includes huge Ikea, Obi, Ashan and probably couple hundret different shops, restaurants etc. If you want to make it easy and find everything in the same place, try this huge place worth to just see.
This tip has the address "Crossing of Murmanskoye Soshe and KAD."