I'm also looking to travel on a baltic cruise specifically to Russia as a port(posted a few days ago here). How much time do you have off? I was hoping to sail transatlantic and then do the baltic cruise perhaps with a few days break on land between. Any interest? The Epic is currently charging $399 to cross the pond in 11 nights, which would less than airfare.
I might be able find a separate roomy for that leg but it limits which cruises I can take as most transatlantics happen late april/early may.