"....tourist things that just aren't worth the time."

The town of Kailua-Kona, except perhaps for a few of the historic sites.

My favorite beach on the island is Manini'owali, just a few miles south of Four Seasons Hualalai; beautiful crystal clear turquoise waters, and almost white sand.

I can relate to a panic attack while snorkeling, but I doubt you'd have a problem at Makaiwa Bay, where the Beach Club is. Entry is very easy with a mostly sand bottom and gradual incline. Don't have to go out far to see stuff either.

At the north end of the Mauna Lani Resort property (north of the Fairmont Orchid) there's access to Puako Petroglyph Park & Archeological Preserve. Pretty interesting...

If you make the drive to Hawi, might want to stop at Hamakua Macadamia Nut Co.

Thanks for asking the question. I'll be there at the end of next month, and have gotten a few ideas from some of the responses.

I really liked the seahorse farm. It was really unusual and interesting--and I loved putting my hand in a tank and having them wrap their tail around my finger. Fascinating creatures.

I stayed at the Marriott about six or seven years ago, and the beach out front had an area where sea turtles rested, which was pretty cool.