Oside Jimc
Contributor
I only have experience with Maui & Kauai (Never been to Ohau & when I'm on the big island I get Blue Marlin on the brain), but based on your desire for diving + beaches I'll also have to give the nod to Maui. Kauai has some fantastic shore dives, but except for Tunnels there is no beach involved. Or better still, go to Maui, dive with B&B and you're back at the ramp by 9:30-10:00, just in time to pick up the family and head for the beach for some additional shore dives!