One thing that I miss (and didn't think I would) is a stand-alone Crimean War scenario, somewhat along the lines of the Indian Mutiny.
If you come at this war through the game engine you'll probably have a hard time getting an exactly historical start position. The belligerents probably won't all have developed their resources to the same extent as in the actual war, and the armies and fleets won't be in their proper start positions.
Even if you set the thing up with exactly the same starting forces in the historical start positions, you're still looking at a pretty big range of outcomes: it's by no means certain that the Allies will invade the Crimea once they go over to the offensive. The war might be decided at the gates of Constantinople, or it might involve an Allied grab for Odessa or Georgia.
It's a situation loaded with potentially wild strategic outcomes, and although going after Sevastopol makes sense, it's not the only thing the Allies might have done. So even if you dislike historical simulation because you find it limiting, this is one historical situation where the list of what-ifs can get pretty hairy right off the bat.