At Vero, my pre-teen and teen nephews occupied most of their time with...
pool/slide
ocean/boogie boards
tennis
ping pong
basketball
mini golf
renting movies
exploring
My nephews haven't done HH with us but HH had kayak tours, crabbing, pool/slide, bikes, arts and crafts all at the resort. Outside there was the ocean of course, tennis, mini golf, etc.
I know my nephews loved Vero and after we told them about HH, they would like to visit there one day too.