We stayed at Coconut Cay with our family of 5 (3 kids - ages 15, 14, and 11). This ended up being a great home base for our 4 day stay in Vieques.
Positives:
Great communication with owners before arrival.
Very close to the ferry - 10 minute walk. The ferry was right on time and so economical - book tickets ahead of time for $2 each.
View from pool deck is very picturesque with the waves crashing in the distance.
The home is bigger than it appears in the pictures - lots of space for larger families to relax in the living room, patio area, around the pool.
The pool is also much larger than it looked and great for relaxing after exploring.
Wild horses come to greet you at the property and we always felt safe in the area.
Walkable distance to Black Beard sports where we took a Bioluminescent Bay tour.
Beach chairs and umbrella being provided was really convenient.
Challenges
Many tiles missing from the pool bottom and sides. I wasn't too worried about it at first, but then my son ripped his hand open pretty good on the sharp edges - we luckily avoided stitches and stopped the bleeding but it was a pretty bad cut. This seems like a fixable problem that would greatly enhance the pool experience.
There were multiple areas of cleanliness that were overlooked when we had arrived - moldy coffee remaining in the coffeemaker; two grease filled pans that hadn't been washed in the oven; the counter was sticky with something sweet - lots of ants and it caused any paper that was put on it to peel off. We ended up cleaning all of these areas ourselves but they seemed like basic things that could have been improved.
Also, the microwave didn't work.
Recommendations
We thought we could get away with our three days without a car but we ended up renting a Ford Bronce and are very glad we did so. With the vehicle, we could access the more remote beaches so much more easily. La Playa de Chiva (Blue Beach) is awesome for a secluded beach for young kids. If you park at spot 9 or 10 you can even walk across to the small island on the sandbar.
Snorkeling - bring your own snorkel gear (although there is some basic gear provided) and drive to Punta Arenas (Green Beach). If you're good swimmers you can swim out near the white buoy (or just follow the snorkel tour groups). We saw sea turtles, sting rays, tons of tropical fish, and there was even a nurse shark (harmless).
Overall, it was a great place to stay on Vieques for our family.