I don't think I remember exactly WHEN you were scheduled to visit Hawai'i, but please realize that the winter-time has the largest influx of folks from all over the world...including the numerous ships docking at the harbors. The Ala Moana Hotel, as has been mentioned, is located within a walk over a bridge to the shopping center. Don't plan on buying anything cheap.......the Ala
Moana Shopping Center was built for the ulta-rich from across the waters! Instead, take the bus around the Island of Oahu, see the different things offered, ie: North Shore with magnificent surf, Haunama Bay, USS Arizona, and possibly Waikele Shopping Center, or the Ward Warehouse Center.

Taking a couple days to visit the VNP (my backyard!), just know there is not a dirth of hotels on the east side of the Big Island of Hawai'i. There are multiple B&B's, with some nice (not glitzy) inns around the volcano area. Look on the internet under "volcano hotels" for a place to stay. It is about an hours' drive from Hilo town, so it would be worth your while to try to stay near the VNP. After you enter the park, you will have access to information on whatever you would like to do. The Observatory for the volcanologists working there is open to the public, and you can ask to speak with any of the geologists or volcanologists on duty. These folks are dedicated to their jobs, and always seek the opportunity to "teach" those who have an interest in volcanos. Hopefully you will enjoy the Big Island, and Hawai'i, in general, and you might save up for another trip to the most isolated landmass in the world!