What are the best things that I can do in Hawaii besides just going to the beach and shop?

Aloha

Sounds like you're going to both Oahu and the Big Island where Hilo is located

On Oahu I suggest:

Pearl Harbor, Dole Plantation, North Shore Surf, Polynesian Cultural Center, Valley of Temples, Pali lookout, hike Diamond Head, Waikiki Aquarium, ALoha Swap Meet, International marketplace, if you're going end of 2011 go whale watching

On Big Island I suggest:

Volcanos National Park, a cruise to see the lava enter the sea, watch for honu (turtles) on black sand beaches, night snorkel with manta rays, visit the Kona coffee plantation, Akaka falls state park, Puukohola Heiau (temple) National Historical Site - and much more

If you need any planning help let me know, I'm a travel agent and I LOVE Hawaii =)

Melissa

In Honolulu you could always visit the Pearl Harbor museum. Even if you're not a history buff, its a good place to visit just to see.

Look for tours of inland Hawaii. Many people don't realize that once you leave the beach, Hawaii is covered in rainforest. There are also many beautiful rivers and waterfalls you can see.

If you're staying in a hotel, I'm sure there will be brochures by the front desk of things/places to see as well.

Go fishing