Hi,
Don't know how interested you are in this sort of thing, but we recently went on a short break to somewhere called "Sandyballs" (haha, yes that name is for real).
It's in the UK so not very exotic, but it's run by Away Resorts which is a sort of cheaper Butlins, catering more to families with younger children.
We took our kids, both under 4, and they had a great time. There's a pool which has two mini splash pools, a small soft play, some organised fun before bedtime. You can rent bikes with trailers or child seats, as well as cosy coupes and trikes.
Restaurants and cafes on site which is very handy and a short drive away there's a small town with a massive outdoor play area. You can choose from staying in a lodge or caravan if I remember rightly.
I don't know maybe not everyone's cup of tea but I liked everything being so readily available and like I said I think it catered well for very littlies.
Hope you find what you're looking for!