I've found the BBH Bamboos to take ages to dry as well.. even in the 35 degree windy days we've been having. As I only use the Bamboos at night, I made sure I bought a few to allow for drying time... but they are well worth the wait!

ChrissyT - I'd invest in a wool soaker (or knit one yourself if you can) as it works so well for lots of people as an overnight nappy combo with the BBH Bamboo. So far, I've never needed to use anythign other than the boosters the nappy comes with and Xander still has a night feed, sometimes two!
As to how often I go between changes, I prefer to change Xander every couple of hours (even if he isn't very wet) during the day with lots of nappy free time too. I know that if I wanted to, the nappies would last just as long as any sposie timewise.