The Republic expansion for Crusader Kings II is already promising to play things out differently. With your place in one of the merchant cities of the era being your source of success, the latest dev diary for the game is appropriately themed: "War and Trade".
Trade is going to be the lifeblood of your rise to power, so the new focus on Merchant Republics is the focus. The full diary will teach you the difference between Trade Zones and Trade Posts, and which vital roles they will play in the game. You'll want to be the one in control of a Trade Post - just a hint. Power in merchant republics is hard fought, so there will be a lot of conflict over these points and more.
Anticipate that Trade Posts will be heavily contested throughout the game. But if you're the one to come out on top, control, and maintain these routes and posts, then you'll definitely be well on your way to great control and success.
The Republic will be out in early 2013.