Moved to the Bay Area in 12/13, so naturally, with a heavy training calendar for 2014, I needed to run the world's oldest --103 years in 2014-- road race, B2B, in San Francisco. Everything you've heard about the race is true, such as crazy costumes, wildly inebriated and/or high spectators, a sea of humanity running it officially (28,000+ this year), and the Google Images can speak for themselves.

I ran the race as an actual race, a tune-up for a goal marathon two weeks later, and starting in the sub-seeded/seeded/elite corral made things a lot easier for me, in terms of dodging crazy spectators and other runners. I think that's the most important take-away from this race. You can self-seed when you register (though you might have to provide proof of a qualifying time for the first corral; I don't remember), and if you want to actually race it, then that's where you want to start. If you're down for just a training run, irrespective of time and pace, then it doesn't matter.

Logistics can be kinda a crapshoot with the point-to-point course, but you can get around afterward on public transit, Uber, and the like, but the city gets kinda locked down a bit between all the spectator madness and post-run parade that B2B spawns (and this year at least, a baseball game).

All told, I'd recommend doing B2B at least once. It was fun and despite the crazy spectators who made their way onto the course, the race was actually seemingly well-managed for the most part.

More details about my race: http://www.runningruminations.com/?p=1667