Hi Cwright!!!
I'm new to the forum as well... And just got engaged... Started realizing all the work we have to do towards "the big day"...
First of all, I see your concern regarding weather, I wouldn't worry so much about it, since Mayan Riviera area is usually warm all year around, just so you know, I'm mexican, so I know what I'm talking about.
I've been doing some research, and according to my math, should be around 25,000 USD including attires, flight, hotel and wedding ceremony and reception, that considering +-/ 60 guests. We haven't picked a Resort yet, but after surfing on the internet, I would suggest you to look into: Dreams Riviera Cancun, Palace Resorts, Paradisus, Real Resorts, Now Resorts and Barceló Mayan Palace... They all have pros and cons, it all depends on what you want and how much your guests can spend to come to your wedding.
Hope this clarifies some of your questions.
Good luck planning!