Age of Worms and WotBS both took about 18 months of 3-4 hours per week. On Kingmaker #1 we've spent a month on the first adventure but I don't know how far though it we are.
My group is finishing WotBS 4e this month. (Like, literally. Our last session ended in middle of the last fight. We have one session to go.)
Including the last session, we will have played 108 sessions, or about 324 hours. (Two non-stop weeks!) We started playing August 2010, so that's a solid three and half years of entertainment.
Damn good value.

(Incidentally, I'm pretty stoked about finishing my first full-30-level campaign EVER.
