The baltic Sea Cruise was a great way to see all these wonderful countries, rich in history, beautiful country side. Getting on and off the ship was a breeze, even in Russia where the immigration is very well scrutinized.
I traveled solo and met a wonderful group of solo travelers. It made the adventures in each country more fun with the company of other solo travelers. I found the food was good (absolutely loved Teppanyaki where they cook the food right at your table - bring all your friends from a very fun time and great food!)
I didn't do excursions at all ports, only in St Petersburg (needed to have a tour to get off the ship. I understand visas are hard to come by otherwise). But most ports had the hop on hop off bus which I found to be a great way to see the city at a reasonable price. You could get off and on at will.
I love the studios... first, I only pay for one person... they are compact, but doesn't feel cramped. The studio lounge is great... It's fun to show up for a cup of coffee and find others there for an impromptu chat. Loved the solo meet & greets. I've made some amazing friends through this.