That was some tasty cerveza, indeed! 

A side note on Paul's comment: this super far out lady in Mexico City told me and a friend to go to El Panchan, which, I guess is practically the same place as Palenque?! Incidentally, she was also a total 2012er (way back in 2001!). Go there!

Puerto Morelos is a cute little town a 20-minute taxi ride south of Cancun. It's got affordable, nice little hotels away from the touristy mega-hotels, and it's got the touristy mega-hotels. It's also a reasonable bus ride away from ruins at Tulum, ferry ride to Cozumel from Playa del Carmen, snorkeling at Xcaret.

I travel annually to do fieldwork in Ecuador. there is jungle there. There is beach. I've been to both and there is much to recommend them.

But I spend my time in the Highlands. If you want an awesome city to visit with a lot of great art, a nice climate, great mountain parks in the vicinity for hiking/horseback riding, and a funky atmosphere that is a combination of European and indigenous cultures, I nominate the city of Cuenca. Cuenca was once the northern capital of the Incan empire.

I have stayed there several times for several weeks to take intensive language classes and have loved every minute of being there. Some good hostals are as cheap as $15 a night. Food is reasonable, etc.

If you go, be sure to plan for a couple of days to visit Saraguro (about a 3-hour bus ride south of Cuenca), which is a distinctive community with a strong indigenous identity (it's where I do fieldwork). They would love to host you and collect some of the discretionary spending you have available in order to support their economic opportunities.

If you want to think the other side of the world, think Sri Lanka.  Great scenery, great food (all sorts of varieties - Colombo is a foodie paradise) and Geoffrey Bawa architecture (including hotels on the coast and built into the jungle - yes, incorporating the jungle into the architecture). Oh, and dirt cheap and off the beaten path.

My Sri Lankan "office" http://www.paradiseroadsl.com/cafe/Introduction.html (the music is not so repetitive when you're actually there).

I'm going to ditto Davids on the Highlands, except I'm going with the Guatemalan Highlands.  Especially up north Quetzaltenango and HueHueTenango for your purposes.  There are language and culture schools there for people who want to learn Mayan.  And my favorite poet, Humberto Akabal (http://akabal.com/) is from that neighborhood.  This is not exactly jungle, but you could get there from there.  Palenqueand even Tikal are not far as the crow flies through the jungle.  

In Mexico's southern border region you also have Chiapas which could be sketchy in a US State Department Travel advisory sort of way but it is also awesome.  

Next another road-less-traveled area I would consider the Pacific Coast of Central America.  Great surfing and ambience in El Salvador but bring some great flip flops because those gorgeous black volcanic sand beaches will scald your feet.  

I appreciate Vicarious comment about not telling too much about places.  The last thing most places in the world need is more Americans.  Then again, PDDers aren't exactly Americans, are they?  

Finally, I have no idea what I am talking about.  It has been 15 years since I was south of the US Border and for all I know these places are all ruined and overrun with tourists, bottled soda, and patchouli-drenched, dreadlocked American ex-pats by now.

Puerto Viejo, Costa Rica. The best.