My idea is to meet up at Iao Valley. Your parents can walk around, enjoy the cool, look at the sites, or go into Wailuku or Kahului while we run around. Wear stuff you can totally trash, and bring a change of clothes. Assume you're going to get wet and muddy. If your parents like to hike, there are 2 decent hikes that I can show them.
You can do a little regular parkour at the beginning, if it isn't too crowded. I'm planning to head upstream/ into the forest for Methode Naturelle inspired training - which means we'll be walking, running, jumping, crawling, climbing, balancing, lifting, carrying, throwing, catching, swimming [tho the water's very shallow], and maybe some sumo wrestling or something.
For time: It's really best at like 10 am... I'll try to get in touch with Shiloh. I think it will be more fun with 4 [or 6 if your parents want to join in].