Ladies picking a resort is really the toughest part. We were engaged for 5 months before we went for our site visit. I will preface this by saying that we were in cancun for another wedding so we had ONE DAY to look at resorts.
You will overwhelm yourself. You will feel frsutrated. You will look at a ton of places and not know which one is the best. I would be realistic - what really worked well for us was narrowing it down to 5 resorts that we looked at that met our criteria.
For two months before we went, FI and I had a lot of talks about what was important. 1) family friendly 2) within 30 min drive of cancun airport 3) within our one week guest budget 4) opportunity for private reception 5) One wedding a day, non negotiable 6) all-inclusive 7) private ceremony beach front property.
I looked at every resort in Mexico and the Dominican. I started crossing resorts off the list that didn't meet the criteria (non-negotiable). We visited: the Paradisus, Azul, Dreams Cancun, and the Grand Palladium. Could be have looked at 12 more? Absolutely - but I knew I would drive myself nuts.
Once we picked the resort it really got easier. Now I can jsut deal with all the fun stuff!