We were just on the Big Island over Christmas. Hapuna Beach is a truly amazing gorgeous beach. Our boys had such fun body surfing.
We stayed at the Outrigger Kanaloa at Kona which is further south on the island in Kailua-Kona (still easy driving distance to Hapuna Beach and other sites) The Outrigger Kanaloa had a 2 bedroom suite, full kitchen on the golf course. They also have ocean view suites. Very nice, clean, reasonable price.
We stayed in Hilo at the Hilo Hawaiian.
It was a wonderful holiday - you will love it!