Welcome! Picking a location is certainly the toughest decision - it took us four months - I started here researching and then came up with a list of about 10 places that I spent a lot of time comparing - one thing you may want to consider is how much you want guests/yourself to spend for a week all-inclusive.
We decided on the timing first - once we knew we wanted end of November we started looking at pricing of the 10 or so resorts. For us one big item was that we wanted a resort that only does one wedding a day - there are a limited number of AI's that do one a day so we were able to narrow it down that way. Then we looked at prices of the top 5 or so.
We were down in Mexio this past fall for a wedding and went to look at the Grand Palladium, Riu Riviera, Dreams Cancun, Bahia Principe and Paradisus which were our top five and ended up with Paradisus.
Hope that helps!