Island hopping using the Metro or buses is easy. Beautiful sunny evenings where tourists and locals stroll around areas such as St Peter & Paul fortress. There was also a free gig outside the Winter Palace today, this happens quite a lot.
With White Nights coming up, there’ll be more, a lovely time of year to visit:
http://www.saint-petersburg.com/virtual-tour/whitenights/Seen quite a few cyclists around and there are hire bikes: