The highlights of my trip to St. Petersburg were definitely visiting Peterhof and The Hermitage, taking a boat trip around the city, and experiencing the "white nights." Not much sleep was had during this trip, but it was amazing how much we could cram into a day and a half.
Quick Tips:
It is very useful if you are a student to get an ISIC card. This got us cheaper train fares, free entry to Hermitage, and cheaper entry to other sights all over St. Petersburg.
If you are getting a boat trip, make sure to check if they do it in English. Ours didn't, but luckily we were there with some Russians who could translate for us.
Best Way To Get Around:
Again, like Moscow, the metro is heavily used around St.Petersburg. Although it is not as big as the Moscow subway, it is still as clean and efficient. Walking around St. Petersburg is also quite easy if you stay near the centre, as many of the sights are quite close together. We took a boat ride to Peterhof, which had amazing views of St. Petersburg and took little time to get to Peterhof. Buses can also be used ,but can get really crowded and hot. If the journey is quite long, you can be squashed in a hot, sweaty bus for a long time.