Best locations for long term stays?

I’m recently retired and my wife and I want to spend a year in a Caribbean locations. We need your advice!

We have three kids, 3, 5, and 7. They love the beach.

We have been to jamaica, Cancun, Tulum, Cabo, etc and love it.

We want to find an apartment on or close to the beach.

We know some Spanish and are planning to get better before the move!

What’s the best spots to do this?

Inexpensive cost of living locations? Best websites to find rental apartments?

Concerns we should be made aware of?

Any and all advice is appreciated!