Most every island in the Caribbean has a few nice resorts to stay and relax.  Question becomes what you want to do with the non-relaxation time and how hard you want it to be to get there!  One of my favorite places for activity, history, culture and relaxation is San Juan.  And you don't need a passport to get there.  The Old San Juan, is full of colorful buildings, great restaurants and San Juan National Historic Site , Castillo San Felipe del Morro and Castillo de San Cristóbalare fun to walk around and take in the history.  You could spend some of the time staying in the city and then head an hour or so out of San Juan to stay at an excellent resort for the relaxation portion, someplace like Dorado Beach, a Ritz-Carlton Reserve.  The interior of the island has hiking, rain forests and water falls.  Check out Junglequí Adventure Park.  You can scuba & snorkel in multiple places around the island too.

Enjoy planning your honeymoon.  Hope you find the ideas helpful!

Have you considered Belize?  Caye Caulker belize is known for it's "Go Slow" approach, and has ample opportunities to head off for some snorkeling/diving or trips to the mainland to visit Maya ruins or partake in other active adventures.

If you want a little more bustle, right nearby is Ambergris Caye, Belize which is a little bigger and has some more to do on the island, but still offers the best of active opportunities.

Heading further south to Placencia is also an option, with some different activities available and perhaps some more beaches.

One benefit of Belize vs. other Central American locations is that English is the native tongue, which may make communication a little easier.

As with anywhere in the Caribbean this time of year, however, do keep an eye on the tropical weather forecasts, and consider looking into travel insurance.

Ha! I think you will get more confused here since I'm sure everyone has a favorite spot. We just visited Barbados recently and had an amazing time. I produce a travel show with a teenager who loves the beach and surfing, but he also likes visiting places that offer him new things to do and that has an exciting cultural life. Barbados gave him all of that. Last weekend we posted our first episode "Summer for Summer" at www.bookertravels.com and will keep putting up new travel videos on Barbados for the next 2 months. In one week we surfed, explored tidal pools and caves, got on a boat to fish barracudas, tried wonderful new dishes and fruits, learned about tropical flowers, and relaxed in some of the most beautiful beaches we have ever seen. On the tips section of our site we list what, how and why. But don't miss taking a surfing class with some of the coolest people you will ever meet. My recommendations: Zed's Surfing Adventure Barbados and Barry's Surf Barbados.