We just returned from our Baltic Cruise on the Emerald Princess. The cruise was terrific but I was especially pleased with the custom tour we arranged with Russian Tour Guide. We had 2 action packed days with some very specific requirements . Steve Fowler is based in the US with his partners in St. Petersburg ( and Moscow) and he helped me work out a very custom tour that was terrific and cost a fraction of the cost of a cruise ship excursion.
Their web site is www.russiantourguide.com