Funny you should mention 5K's D.H., there's one running tomorrow in a town just 10 miles from here. I'm considering going, but it'll depend on how I feel, it's a little soon after the marathon. It'll be a last minute decision, but I'm leaning towards going, even if I don't race.
There's also a half marathon running on October 21st, the CHAD (Children's Hospital at Dartmouth) Half Marathon. After training for a Full, a half marathon might be a fun distance to run.