Ebonyr, what's the flavor of the city?  The reason why I ask is that I created something similar a few years back for a city that was in decline.  Overtime the flavor changed and it became more lawless.  When it did, I came to the realization that a single bridge between each island created choke or control points that the city's various power brokers wouldn't appreciate.  I added more bridges, many of them a stiff breeze away from collapse, and it really helped to create the visual impact that matched what I was trying to create.  
In a multi-island city, the flow of people and goods becomes more of an issue.  Why should people want to build and live on a small island?  Just a few thoughts.