The chance to experience off-road riding with a focus on bike control would be awesome. It so happens that Yamaha offers just such a course a pretty hour and a half ride north of me. That would be a fantastic day in the dirt.
#5 Kawasaki Z1000
The anime dream machine. Twitchy, not as good as other naked bikes according to Bike, but it's one I got excited about throwing a leg over and I'd never get tired of looking at it, though it makes little sense and would be a handful. What's a mid-life crisis without making silly, emotional choices?
The start of an ongoing cafe racer makeover. The basic bike is sufficiently hooliganish so it speaks loudly to that vanishing sense of immaturity. This bike begs for leathers and old school style. I'd ride it like a rocker to pub brawls. This Thruxton would turn into the bike I'd ride to Fight Club. It wouldn't be shiny for long, more like a rolling black eye.
#3 Royal Enfield Bullet Classic
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#2 Leather pants... or worse!
In my year of riding I've come to appreciate leather riding gear for the level of protection it gives. I've also come to realize how much more effective leather is at keeping you warm in less than comfortable Canadian riding conditions.
All that aside, leather looks cool! If not the pants, then a full race suit and some track days to wear it in on.
#1 Suzuki Hayabusa or Kawasaki ZX-14R
Oddly enough, the whole adventure bike thing doesn't seem to tickle the mid-life crisis itch, though perhaps it's because adventure riding is so far away from normal life while a road bike is a daily opportunity. To make the list the adventure bike deal would have to get all Ted Simons (I'm reading Jupiter's Travels at the moment) and involve a long term opportunity to travel too. I get the sense that another post is forming around this.