I have houses and MTY and in Fort Lauderdale, so I am VERY familiar with the drill. No way you need to be there three hours in advance.
There is a premium check in line (business class, I think it says) that I always use because I'm EXP. I see you're gold, but you could probably use that line anyway and not get lambasted.
I usually try to get there about 90 minutes before the flight. I have been there about 60 before and not had a problem (not checking bags if 60 minutes).
Security is a breeze (no laptops out, shoe removal) and if you set off the detector, they just "wand" you right there. None of that TSA nonsense of "male assist on line 1, female assist on line 2" nonsense.
No AC, but there's an AMEX Centurion lounge you can get into if you have an American Express Gold or higher.
If your flight leaves midday, be sure to allow time to get to the airport as traffic can be heavy (morning, mid-afternoon and late afternoon/evening).
Business or pleasure? There are lots of things to do there - hiking in the national park or high end shopping in Colonia del Valle. I'm afraid Starbucks has taken over, however...
Enjoy!