11 Extra Days in Mexico - What to do?!

We booked to go to Mexico with friends next April for 15 nights but some changes at work mean that we’ve extended the trip to 26 nights. Only problem is choosing what to do with the extra 10-11 nights. What we’ve got planned so far:

Days 1-3 Mexico City

Days 3-9 Puerto Escondido

Days 10 – 12 San Jose Del Pacifico

Days 12 – 15 Oaxaca City

We’ll wave our friends off on Day 15. What should we do next?! I have no knowledge of Mexico and usually do lots of research but Mexico is so big that it’s tough to know where to start.

Flights go from Oaxaca to: Monterrey, Cancun, Guadalajara, Tijuana so I’m not ruling out the possibility of going elsewhere (Cancun doesn’t appeal though) but Oaxaca state gets rave reviews so should we stay and explore (if so please give recommendations) or move on via plane or bus and see something different?

We’re in our mid 40s but no kids etc so quite young at heart… we love food, ancient ruins, not averse to smoking a bit of weed, obviously love a nice beach but we don’t have to spend the whole time sat on one. We’re up for anything really, the only hard “no” the mrs has given is jungle/mountain trekking for days

Thanks!