Jolie,
Have you thought about going on a timeshare tour vacation and checking out all the places in the area that you are interested in that are for sale? I have done this and I found it interesting,fun,profitable. Many resorts will pay you to go on timeshare presentations and then you look at all the resorts and then decide which one you want to buy. Only you go home and think about some more and then buy RESALE.
Alot of people will post they don't want to waste their vacation time by going to timeshare presentations, but it is the best way to see all the resorts and know what they cost from the developer.
I own alot of time in Mexico and like yourself I love the idea of it being RTU. I often let people regarding timeshare that a lifetime if way toooo long.
I truely envy you, as you have so much information at your fingertips and there is so much resale out there. Just take your time, there is not just one deal or one unit. If it is standing for 2 years it has resale.
I love the Playa Del Carmen area south of Cancun. I own at Sunset Fishermen's Village with a resale contract and optional all-inclusive. This resort is my favorite place in Mexico. It is so sad

that they have such a bad reputation because of their sales staff. I also own 4 weeks at Cabo Villas Beach Resort and I also love that small resort. It has the best location in Cabo right on Medano Beach. The rooms are nothing fancy, but the staff is great and the resort is oceanfront and very close to town.
I bought both of these resorts after touring them, and then buying them resale. Fishermen's from Holiday Group and Cabo Villas off of ebay.
Have Fun