We wanted to come back before we'd even left! We chose Hacienda Tamarindo based on a combination of the positive reviews and relatively low cost, and it was an excellent decision. The place really is beautiful--great views from the pool and the main building, lovely breakfast area under the Tamarind tree, many nice little interesting spaces to hang out. We went for one of the cheaper bedroom without a view, which worked fine for us--it was a large room with a nice bathroom and there were plenty of other places to get a good view. That said, if we went back we still might go for an upgrade just to mix it up.
It's also worth commenting on the Vieques experience itself. If you're looking for a lot of commercial amenities, this is not the island for you. If, however, you want the most important decision of the day to be which beautiful remote beach you drive your rented 4 wheel drive vehicle to, then book yourself a trip to Vieques.More