St Petersburg is definitely my favourite city so far, as you get to see everything in a couple of days. It is such a beautiful city with canals, lovely palaces, the Hermitage and really pretty churches like 'The Church of the Spilt Blood'
This is also the best time of year to come as it is just before the season really takes off so there are not that many tourists around and the weather is pretty good. The only downside is that you only get 2 hours of darkness at night which takes a bit of getting used to, oh and the Russian drivers which I've decided are the worst I've ever come across! (so far)