My family and I love Hapuna Beach Prince hotel and will not stay anywhere else while on the Big Island. We are headed back in June. If direct access to a great beach is important, then Hapuna is (by far) the best option on the Big Island. The grounds are nicely done, and the hotel has only 350 rooms and has a very relaxed feel to it. If relaxing, hanging out at the beach and pool, playing golf and not doing much else is a priority, this is the place. Anyone staying at Hapuna also has complete access to the adjacent Mauna Kea resort as well.
Regarding VNP, I find it to be one of the most interesting places on the planet, but then I am a geologist so I probably would. Too often, people do a quick trip to the Park and never get out of the car to really see the place. You will find landscapes and other features found nowhere else. It is well worth the visit.