i have 2 ideas for you.
First, take them on a day sail.
Second, order 2 copies of the Cruising guide for BVIs. Once they get a hold of it, they will find lots of great things to do.
Oh also, the first time we went to the BVIs, I let my wife plan the entire route. She loved the idea, and it made her feel like a big part of it.
Sometime before the trip, get your wife(first mate I assume) on the wheel and go over hand signals. Yelling at your wife in a mooring field is strictly prohibited LOL.
Oh, get a copy of the video from the charter company.