I have 3 WL books waiting for people to respond yes or no (one is already on the second request). My account is going on vacation hold tomorrow. What happens to the requests if people don't respond in time?

If people don't respond, the Vacation Hold will catch the books and they will not roll to the next wisher. When the Vacation Hold expires, they will be offered again. The current requesters will still be able to accept the offers until their 48hrs expires even if your Vacation Hold has went into effect, it doesn't affect active transations.

If I were you, I'd put your acct. on vacatoin hold NOW - don't wait until tomorrow.  As Melanie says, it will stop the books from rolling over to the next wisher, who would then have 48 more hours to respond.

Put your account on hold - go on vaction - have a wonderful time - when you get back see what you have - don't worry about it - it'll all work out just fine.

PS - Really - have a great time ! ! !