Since you are renting a car how about spending a day of driving and visiting many different beaches and areas of the island. You can still start off your morning with breakfast at L'Escale and end your day with dinner at Calmos.
You could hit 3 or 4 beaches, like Orient, Friar's Bay(have lunch), Bay Rouge, Mullet Beach, Maho or others of the 32 additional beaches on the island. You can walk the beaches and swim some without renting chairs and parking yourself on any one beach for the day. If you visit Friar's Bay you could do a short hike and visit Happy Bay and back. You could really get a taste of the island and a feel for the beaches.
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