We are bringing the first adventure of the "new" D&D play-by-email to a close (I use the quotes because it's been going on for more than three months now), slightly faster than I expected. The PCs have succeeded in their initial adventure (retrieve the crown of the King of Birds, which has been stolen by a lizardman, in time for the holiday and the coronation), and are enjoying their safe return to the village. We are in the midst of a lovely little country celebration/dance scene, which is giving everyone a chance to explore their character's inner lives a bit, and how they interact with people outside the party. Players are grasping onto the romance theme I'd like to nurture in this first arc with fair enthusiasm.
We'll spend a few weeks doing interim stuff--divvying up treasure, buying new equipment, developing some background events--before we jump into the second adventure. If we can keep the fights moving at the relatively snappy pace we managed for the first, I expect this one will take around six months.
One thing I'm taking away to work on as I plan, is making sure to include opportunities for everyone to show off, since some players are more reluctant than others to put themselves forward.