Luxury Hotel off the beaten path celebration?
 

My husband and I are looking for a boutique resort in the Caribbean or Central America where we can leave our kids behind and celebrate my 40th birthday. We are looking for something that is luxurious, but not pretentious. (Doesn't necessarily need to be fancy) Someplace Relaxed, but that still offers excellent service. Quiet would be great- we want to be able to eat well and drink well, but aren't looking to stay up late partying. Adults only would be a huge bonus! A resort off the beaten path would be wonderful. We are willing to fly someplace and then travel to get to the hotel.

We found such a place outside of Todos Santos, Mexico (Rancho Pescadero) and our stay there was amazing!! We would return there, but We have relocated to he east coast and are looking for that same kind of resort in a different part of the world!

My sister and her husband love Guana Island. They've been quite a few times.

http://www.guana.com/

While I have your attention, could you tell me this about Rancho Pescadero--is there a pool large enough for swimming laps that is heated and warm in the winter months? Thanks!!

There are lots of boutique resorts on St. Barts. You didn't mention a budget but be prepared for high prices almost everywhere. St. Jean Beach is the most active beach with a few hotels and restaurants but there are other hotels that are pretty quiet. Consider these:

Le Sereno
http://www.serenohotels.com/property/le-sereno/

Le Toiny
http://www.letoiny.com

Hotel Christopher
http://www.hotelchristopher.com/en/

and others. I haven't stayed at any of these properties so I can't personally recommend them but I wouldn't hesitate to stay at any of them. We love Eden Rock but it's right on St. Jean Beach and may not be what you're looking for.

Another island that might meet your criteria is Antigua. There are some nice properties there that aren't in the middle of everything. Look at Curtin Bluff, Carlisle Bay, Jumby Bay and Cocobay Resort.

Any Sandals Resort should serve your purpose. They are all inclusive, adults only with excellent service. We had a wonderful 20th anniversary celebration in one in Jamaica several years ago.
We also had a a great experience similar to what you are looking for in Turks and Caicos last year, in West Indian Resort. Not an all inclusive but more a "condo style", super quite, with 2 pools, a good restaurant, one equally good beach front cafe, open late quite bar, located in a paradisiacal beach, driving distant to several haute-cuisine restaurants.
We spend 5 relaxing days mostly on the beach, only did one organized tour for snorkeling. We rented a car from a local company (from home thru internet) that allowed us to enjoy multiple wonderful dining experiences.
We are planning same type of short vacation again this year in Grand Cayman, which I've read is wonderful too.

Three places come to mind.

First, the Horned Dorset Primavera in Puerto Rico (Rincon, about 2.5 hours from San Juan). The town itself is a surfing/beach town, and the resort is set off a bit. The suites are large and luxe, with their own private plunge pools; the grounds are lush. First rate restaurants on site.

My personal favorite is Nisbet Plantation on Nevis. Built on the grounds of an old plantation, and consisting of small buildings holding at most 4 suites. Cozy and genteel, like the island itself, and right on the island's best beach. The friendliest and most thoughtful (but least obtrusive) service I've ever encountered.

Also, if you don't require being on a beach, Ottley's Plantation on St. Kitt's is spectacularly sited on the slope of the island's tallest peak. Lush and green, with lovely personal service. You can stay in the main house, or in small cottages (with plunge pools). Watch the vervet monkeys cavorting in the trees in the morning and at dusk.