2 Flights in a bracket as follows:

Flight MIA - CUN
drive to Playa Del Carmen, dive Playacar Reef. drink tequila, dance on bars (in that order).

Also - get some CENOTE diving in!

Repeat for 2-3 days.
drive back to CUN
Flight CUN - HAV (Havana Cuba)
Do Cuban things for 3-4 nights
Flight HAV- CUN
Flight CUN- MIA.

Can use points for flights to CUN and hotels in Mexico.