Great thread. I started on a ER6n (naked 650) and based on my personal level of maturity, experience, and self confidence, it felt right. The statement below sums it up:
...Before considering the purchase of a motorcycle I asked myself why I truly wanted one. And none of my answers included girls, wheelies, insane speeds or what I look like to others, i.e. ego...
I wanted to ride "my ride". I actually don't have any riding buddies, and though it kinda sucks sometimes, I enjoy doing things solo just as much as with a group, it also makes it easier to ride your own pace. Motorcycling was that ONE thing I've always wanted, but always found an excuse to turn away. I thought I couldn't afford it, it was too dangerous, or that I just wasn't ready. Then it hit me, I'm going to die without ever owning my own motorcycle. Not quite a midlife crisis, but still a personal epiphany. So I took the MSF course, loved it, and rode the ER6n for nearly 7000 miles year-round in Denver (all street, commuting in traffic, and mountain rides). I had one spill, trying to get home before the snow hit. I hit black ice and the bike washed at slow speed, not much damage but enough to remove the scare of the dreaded "first crash".
I learned a LOT with that bike, how to roll on the throttle smoothly, apply brakes quickly in a controlled manner, and most importantly I focused on what the machine was telling me in different conditions, how different surfaces feel at different temperatures and weather conditions, how the bike's weight shifts when applying the brakes and throttle in varying degrees. I focused solely on learning to ride well (and navigate morning rush hour). Having a lot of experience with mountain biking and autos at the track, motorcycles just felt right.
Then and now, every ride, I am still learning and finding new ways to enjoy it. I now have a 2011 Z1000 and love it. I know the bike is capable of more than I am and it probably always will, but I'm OK with that.
I guess I'm one of the lucky ones, it just comes naturally. Some may REALLY want it, but they're just not wired for it. The most important thing is to acknowledge when something just isn't right for you and accept it.