Tip: Do not take the NCL shore excursion into Stockholm (we took the "Stockholm On Your Own" NCL Shore Excursion). Way too expensive and you have to report to the Lounge at 7:05 AM!!! Totally unecessary. We were dropped off in town by the bus before 9:00, but nothing opened before 10:00!! We met friends who just took the train in themselves around 9:30. Faster and less expensive (the train schedule is posted in the Shore Excursion office on ship).
We recommend that you take the boat cruise and wander around the market near where the boats depart. The Old Town is well worth a half day wandering around. Try to catch the changing of the guard at the Palace.
Busy, busy, busy. The day trips are nothing short of amazing. So much gilt. Hard to imagine living in such splendour. Small wonder the peasants revolted. We also took an evening "Fun Tour" with spB Tours. It featured a drive through the city (by bus) and a canal boat ride with live entertainment. It also featured all the vodka you could drink. Our host started to pour it before the bus had even left the pier and it continued to flow for the rest of the evening. We learned much about the proper Russian etiquette for drinking vodka (I just can't seem to remember, however, what it was we learned). Anyway, it certainly was a "Fun Tour".
Easy to do on your own as you can simply walk in but you will miss a lot without a guide. Go up to the old city and wander around. Don't miss the shops at the foot of the old wall. Excellent knitted wears.
Some people were scared off by the 3 hour trip to get in to Berlin from Warnemunde. Too bad. They missed a ton of interesting things to see and do. There is so much to see in this city and so much history. Our day in Berlin was one of the highlights of our trip. The spB tour guide was excellent, superb! Yes, it is a long way in and back again, but it is well worth the trip. Highly recommended.
More 
