Anna, have you read my answer to Franco's letter with the same question, I sent him (and you also) on December, 2?
As I know there will be a kind of salsa festival in St. Petersburg from 31.12.2013 till 4.01.2014 (with all-night party Dec, 31). So you can join it with your friend. Unfortunately organizers of the event have not yet reported about party's venue. You can ask them directly (their names are Yulia and Andre) using email of the festival:
rusnewyearfest@gmail.com.