A wonderful "old town" with a strolling street. Good food if you stay away from the main tourist areas.
Did this on our own (3 days ahead of the cruise) with Rick Steves guide
Loved the Viking Museum, the Nobel Peace Prize Museum, and, believe it or not, the City Hall! This is a very easy walk from the port to the town.
Again on our own with Rick Steves
Skip the 6 hours to/from Berlin (leaving you too little time to do anything there) and do Warnemunde, Rostock and Schwerin. Alla and SPB both offer tours here and if combined with St. Petersburg, you get a discount.
We used Alla and had a great time.
For all stops in St. Petersburg, used SPB. Leba, our guide was the best guide we have had on a tour in a long time. She was so knowledgeably and even though we did a lot, we never felt rushed or short-changed. The small group made it so easy to both hear what she said AND to make some extra stops or extend things a bit on some things. And we just breezed by some of the large Princess tour groups.
Stockholm is fantastic, but the ship gives you sooooooo little time here that it was very frustrating. Definitely see the Vasa museum.
Absolutely LOVED the old town here. We did this on our own with Rick Steves guide, then took the tram out to the new Modern Art Museum. Fantastic! All Estonian artists.