Just back from my first ever cruise and it was the greatest holiday both I and my Mother, who accompanied me, have ever been on. Nearly everything was superb from the food, the ports the cleanliness of the ship, the staff and the bars.
We only went on one planned excursion, the 2 day 'Splendor of Saint Petersburg'. The guide was amazing and we saw some unforgettable sights. However the itinerary was so packed we were knackered and Mum's knee barely survived it. At the other ports we used the free shuttle buses provided, never having to wait for even a minute for one. I thoroughly recommend skipping Brugge and walking round the seaside resort of Blankenburg instead, beautiful town with shops, a pier and some excellent Belgian beer cafés.
Helsinki and Tallinn are also fantastic but Stockholm did nothing for us with lots of homeless beggars as well as parks with sleeping tramps.