Punta Mita would be my choice, if budget allows. With the grandparents and little ones, I'd definitely prioritize staying inside the gates (Punta Mita gated peninsula) and doing a villa rather than a traditional resort.
A few places I'd look at are Four Seasons Punta Mita villas, Kupuri Estates, and Ranchos Estates. They each offer a slightly different experience depending on how much resort access vs. privacy you want.
PVR is an easy airport, and I'd arrange private transfers for both groups. A private boat day would be awesome for the group (again just arrange transportation to the marina).
For April/May 2027, I'd start looking soon, the best options fill up pretty far out (especially earlier in April).
As an alternative (if you want something to compare it to), I would suggest Turks & Caicos. Especially if you want a pristine beach environment, this would be my choice. Grace Bay has some beautiful villas and so do a few other spots on the island. Only thing here is they don't have direct flights year round.
I've done a few of these larger fully staffed villa rentals across MX, the Caribbean, and elsewhere (currently working on one for 27 people in Playacar) so feel free to reach out if you have questions or if you'd like some help!
Luxury & Adventure Family Travel Agent
Personal Travel Concierge
Europe • Africa • S. America
www.voce-travel.com
Kyle.regitz@fora.travel