What an awesome thread! Thanks for getting it back in circulation.

My commute is a 30-miler round trip, and I do it two three times per week.
Pros:
Fun (there's really no other way to describe it.)
Makes me feel a bit closer to my community
Health benefits
Helps prepare me for long distance touring
In a small way, I'm doing my part for the environment

Cons:
Lack of facilities at the office for cleaning/changing
Heat in central Texas during the dog days of summer