I was just there last week and the island was great!!! I did the Golden Eagle Tour, was a blast! Sailed to a beautiful island just off St. Martin for the beach and snorkeling, after got all afternoon to shop around Philipsburg and chill out in Great Bay beach till departure time. Your wife will go mad when she sees all the Jewelry shop in Front Street!
I booked through a company called SXM Deals (
Welcome to sxmdeals.com-Best deals for tours & hotels in St.Maarten / St.Martin) and got a complimentary Golden Eagle shirt with my trip, their website has plenty of info on tours, beaches and everything else you need to know about St. Maarten. You should check them out. I can't say much about land based tours since I didn't get a chance to try them out... Next time!!!