I'm buying my first bike this winter as well, so I've been looking into this a lot. I agree with 0428. Even though I am not a huge fan of sport bikes, the weight and power of the ninjas seem to make them the preferred starter bike. I am getting the 500 and not the 250 because of my size (6'2" 220) and because I want to do highway riding.
The reports seem to be that if you take care of these bikes you can keep them for a while... They also seem to hold a lot of their value, you'll see this as you look at prices of used ones from up to even 10 years ago.