Hi Cfischer,
I personally like the Hillton Waikiola village with its lagoon, art collection ( hundreds of pieces throughout the resort, swimming pools, putting green and nice rooms) - others complian about the hotel feeling Disneyesque but I did not feel that way.
The Prince Website;
http://www.hapunabeachprincehotel.com
does look very nice.
The day trip to the Volcano does look nice ( I went via the Volcano House and the observatory by the large crater.
If the weather is nice you could go up to the observatory at Mauna Loa? ( I think you can get tours to go up there?)
Enjoy!
Regards
TBS