Dreams Las Mareas was really impressive as far as family friendly resorts go. I would definitely have it as a top consideration. The only negative about it is it’s location (about 90 minutes from the airport). It’s really isolated, so it would take a while to get to most excursions, but Guanacaste Park is nearby and there is plenty to do around the resort (snorkel, jet ski, fishing). You could always go to Nicaragua to see the Volcano, but the ride there takes a couple of hours. I would say if they don’t mind potentially spending a couple of hours on the road every day, definitely visit this resort.
[On the bright side, you get to see a lot of the countryside on those car rides]
Sunset at beach/cove
View of sunset from building 7