You've come to the right place James! My suggestion would be to look back through the Cool Wall forum for some examples of what you might be looking for, also the Register Your Rides thread to maybe connect with an owner and ask about their impressions.
My wife rides a 2012 Ninja 650 and she loves it, there are pictures in my blog. It seems plenty fast to me, but there's always a bigger motor right? We almost bought her a Z1000, but after doing some homework the insurance was just going to be too expensive. You should check out the Z though if the Ninja's been good to you.
You didn't specify what size your current Ninja is. I assumed 650?