Gee ke, it's starting to sound like it won't be that restful a holiday.
Let's figure this out. Day 1, arriving and getting acquainted with the place. Day 2, leisurely morning, water taxi, lunch and afternoon in Caye Caulker Day 3, breakfast at Lilly's, cart ride to the southside, stop and check out all resorts on the way back to town Day 4, breakfast at Estelles, cart ride to the northside, lunch at Basils Day 5, tour to ruins Day 6, hire a boat and guide to run up north inside the reef, stop at resorts along the way, stop at Palapa Bar on the return and then have the driver take you through the cut and the river. Drop you on backside and then walk home. Day 7, a little shopping in town, get packed. Day 8, make your way to the airport for departure
Intersperse into all of the above, going to some of the more popular restaurants for dinner and some of the funkier ones too. Catching some live music here and there, beach walking, ocean gazing, (snorkelling if they are into that) and just general relaxing so that your parents become infused with the sun, the sea and the reef rumble that turns us into ACholics.