I think it is a great way to get your guests excited... And cost effective if it is less expensive to book beforehand.. and I would let your guests know that as well!! That they will save money if they book from home beforehand, I think that would make more people book their excursions ahead of time.. Maybe send them out with a chocolate lollipop (the ones you can make from the molds) to add a little something to it!! So it's not like you are just forcing excursions down their throat!! Let us know how it works out!!