Is there a specific race you do annually?
Not anymore. I hardly have time to prepare aside from my weekly runs which are anywhere from a short 5.5 miles, to a longer 8.5 mile run. I average a measly 15 or so miles on a heavy-work filled week, and close to 30 on a more run-filled/ "no time for the gym" week.
I honestly wanted to lose some lbs. I'd gained when I was younger. I ended up really enjoying the solace a nice, paced, peaceful, quiet run brings.
For me the post-run goodies like the food and whatnot. A cool t-shirt always goes a long way as well. Obviously the more you pay, the more you will typically get back in return with regards to treats and giveaways.
Before the girls, I was ramping mileage enough to probably do at least a half, but I never made it that far. I was doing 10k's quasi-frequently at one point. Initially I wanted to get into triathlons since I absolutely love cardio. I do detest cycling though, so there's that. The swimming and the running I can do all day, 'urry day.
FWIW, I've never been anything but a participant in these sort of events. You can tell the ones who've been at it a while vs. the "first annual" ones. Either way, I find them a lot of fun and good way to get your morning run out of the way, and still grab a decent breakfast spread (pancakes anyone?) from time to time.
Bonus points if they have a beer garden. A good scenic view of the Pacific Coast wouldn't hurt either.