First off, for water enthusiasts, the Inn has kayaks, snorkeling gear, and life rafts available, plus a water shuttle that transports guests to nearby Nelsons Dockyard (a next-door bay). A former provisioning locale and West Indies headquarters for the British fleet, Nelsons is a very nicely preserved 18th century port. Today, the ships docked in the marina are not tall-mast trade vessels, but million-dollar racing boats.
Also accessible via the Inns water shuttle, nearby Catherines Café is worth a visit for great food with a view (the steak tartare is better here than at many restaurants in New York!). On Sundays, Catherines is busy with brunch, when many yachtsmen pop in for a meal.
Afterwards, burn off the lunchtime calories by walking 10 minutes from Nelsons to Falmouth Bay the south sides main marina. Ive never seen as many impressive sailing yachts anywhere as I have in Falmouth Bay truly amazing. With numerous regattas, it seems this is where the worlds ultra-wealthy sailors like to spend winter, before moving on to the Mediterranean in the summer. Walk by the security guard on the docks walkway (he wont stop you) for a close-up of the ships soaring masts (some as tall as a 10 story building!).
Falmouth has several excellent restaurants, including the Yacht Club Marina (Italian; ask for a table with a marina view) and Le Cap Horn (French; no view). For a nightcap, stop by Abracadabra, the local dance club which draws a wide mix of locals, foreigners, plus boat owners and crew.