Update:
After trying to bait them into wrapping up the current adventure arc (and speaking to them about it metagame via email), they didn't go along with it. Last night's session, for which I prepared about 8 hours, ended up being a series of confusing discussions about why they shouldn't attack the BBEG. ("We don't have enough proof," "things are too ambiguous," and "what if he is too tough.") What was intended as a straightforward combat that should have taken 30-45 minutes and lead into the "rest" of the adventure (a typical save the small town vs. the evil humanoids mission) was instead replaced with split party investigations, going to brothels, visiting orphanages, street preaching, breaking into buildings - all done by individual characters with no clear goals in mind.
I try to make things as straightforward as possible, but they always find ways around it. The villain in this case was a LE manipulative type, and they totally bought every thing he said (even though the group KNEW he was evil and was trying to destroy the city).
Next session, I'm not even going to try to wrap up anything. I'm just pushing the game ahead a few weeks time and starting things "in media res" to where the action is.
Retreater