My favorite was a Baltic cruise in 2007 for our 30th wedding anniversary on the Star Princess.
I contacted the various local guides and decided Alla was the best for what we were looking for. DW picked out one of their tours. I posted the tour in our roll call, and we ended up with 10 of us (a nice number for a private tour) and after some suggestions, some modifications were made on the tour, which was fabulous. All of us from that tour bonded together very well.
Other ports were Oslo, Stockholm, Talinn, Helsinki, and Gdansk (the last one was on our actual annivesary). Oslo was on only a very few Baltic cruises (and in fact on this itinerary alternated weeks with the port for Berlin). We very much enjoyed Oslo, and were glad it was on the itinerary. Talinn is of course a wonderful port. We found a lot to do in Stockholm. (Actually, there were a lot more to see than we had time for.)
There were dance lessons and a lot of availabilty of dances, which made DW very happy.
And, other than the 8 who joined us on the Alla tour, there was one couple who lived one town away from DW's Mother. We were able to meet them and spend some time with them both before and after the cruise.