The RSSC Baltics cruise was my favorite.
We did book a private guide for one day, through the ship, and she walked all over St. Pete with us. We did not go to a restaurant for lunch (too many other things to do), but did stop at a Blini Kiosk to get something to eat. That was fun. As I tell eevryone who asks (and those that don't too): Take the Moscow excursion. It is a unique experience.
The seas were calm on my sailing - and I sailed there twice.
