This was our second stay in this development (Kulalani), and it's a terrific location; there's a Foodland about a third of a mile away, you have access to the private parking lot of the Mauna Lani Beach Club (it's advisable to arrive early-ish as this beach fills quickly), and a black sand beach is also nearby.
Mauna Lani itself is close enough to the airport and Kona to be convenient but not too close. The larger Waikoloa Beach resort area is a few minutes away with its shops and restaurants, but Mauna Lani is quieter and feels a bit more laid back.
Waikoloa Village is about 6 miles or so up the hill inland (not to be confused with Waikoloa Beach), and the mall there has a number of really nice food-court restaurants when you and your children tire of burgers and chicken strips (Emma's Kitchen has a lovely, garlicky jook with the amount of black pepper you saw Jack use in a Three's Company revenge pasta dish; Village Pizza is much better than any pies you can find near the resorts).
Waimea and the Big Island Brewhaus as well as Merriman's is an easy drive, and when it's time to go up the hill to Mauna Kea and over to Hilo or the volcanoes the roads are also accessible from Mauna Lani.
The property itself is well-appointed and comfortable with a kitchen that's surprisingly well-stocked for a rental. The rental company's concierge was very responsive and helpful, even on the weekend. We're already planning our next trip back, hopefully later this year.