Not a boater but frequent land visitor (with teens in tow)
I would probably suggest 2 days in and around Virgin Gorda instead of Marina Cay. So much to do and see there. Agree Coco Maya is fabulous! My kids really enjoy the Jumbies BBQ at Leverick too. Only runs on Friday's so you would have to consider that. My teens also love: Spring Bay, The Willy T, Horseshoe reef on Anegada, White Bay (probably because I let them drink a Painkiller there!), Sandy Spit, watersports from Oil Nut Bay Marina, Snorkeling Monkey Point, Snorkeling with the turtles off Norman, the live music at Quito's.
I am sure you will do the Baths..... Tip-plan them later in the day after crowds have returned to whence they came. And eat at Mad Dogs instead of Top of the Baths!