I've been watching pricing on tripcentral on the resorts for this May/June (just to give me a rough idea) and have eliminated properties based star rating and on the approximate pricing there (the ones that go well above my guests budget and are lower than 4*), then I went through and eliminated a bunch more based on tripadvisor, reviews and pictures. I
The problem we are facing is some places are telling us that it's too early for a quote lol, when I got in touch with the tripcentral wedding planners they said to contact them again in April/May... so maybe I'm being to hasty in looking right now (For May 2016... but flexible)
A good travel agent will be able to get you a quote from the tour operators well before they are released. (I had my quote in hand and bookings started in June 2014 for my Feb 2016 wedding) your strategy is an excellent one- also look here once you have narrowed it down to your top 3 or so, and see how the wedding planning has been for past brides at your selected resorts. What hidden costs, frustrations or bonuses might sway your final decision!
Sounds like you are doing a great job at finding your perfect resort!!