I'm not sure what altitude you're allowed to after a dive, but there's not much to see without going pretty high, like 8000 feet. You have to get that high to get above the vegetation and really see the volcanic rock/soil and I don't think you can even see the observatories until past 9000. The viewing areas that let you see into the crater are at about 10,000. I vote for a resort day; it looks beautiful!
Molokini is #1 on my list for next trip!