We did this cruise on Celebrity Century a couple of years ago and would recommend a visit to St Catherine's Palace. On the overnight in port Celebrity organised an evening at the ballet, which was an amazing experience and very competitively priced. My husband had no interest in ballet, but quickly changed his mind and still talks about that evening. We've done 20+ cruises, but that was one of the best. Hope you have a fantastic time.
I am booked with Alla this summer and have been very impressed with her prompt replies and good itineraries. I would go private tour to Hermitage as they should get you early entry to avoid the crowds. Ships tours mean you are waiting for the ships coach to fill up, you have to wait when on person wants to go for a potty-stop. I would go private only with 10 people - much more manageable and you avoid the herd instinct.
When I went on a ship's tour(with Royal Caribbean)to the Hermitage, it was very crowded and our party was rushed through to accommodate the schedule of the tour. I wouldn't recommend it.
We went to the Hermitage with RCI and they opened up early for the ships tour, some half hour before the public access. We were first into the museum and had a fantastic comfortable viewing. By the end of the tour the public were coming in from all sides so it was somewhat crowded. I thought the gold room (which we were first in)was overrated and would gladly miss it and its security in favour of seeing more of the fabulous artwork. Join the early ships tour and you will get the best viewing. If I was running the tour I would leave the stragglers and potty-stoppers behind - in Russia they would soon catch up (especially the Americans).
We did this cruise on Celebrity Constellation in May 2006 and it was wonderful. We booked the full 2 days with RED OCTOBER and they were brilliant - but we had a wonderful guy (a fellow cruiser) who organised the whole thing (see 2006 Cruise Critic Boards). It seems the more persons you get to join your Group the cheaper it is with RED OCTOBER so ours was very reasonalbe. Itinery fantastic and tailor made, and no problems. I go away to South America on a land/air tour tomorrow, but will find the time to reply more fully upon my return.