Re the OP asking if 4 nights is too long/not enough:
It depends on how you feel about that part of the Big Island. If you're the type who never wants to leave the resort, 4 days should be plenty. But if you want to experience the Big Island, or even just the Kona (west) Coast where the resort is, you will want more time. It's called the Big Island for good reason. Distances are vast and from Waikoloa you are minimum 30 minutes drive (and up to 3 hours' drive) from anything of significance.