Oahu is the most developed island with big cities (such as Honolulu and neighbouring Waikiki), excellent beaches and a lush, mountainous interior. It's the home of historic Pearl Harbour and the North Shore, famous the world over in surfing circles. Just watching the expert surfers tackle the gigantic waves will take your breath away.
Maui, Hawaii's second-largest island, has lots of quiet beaches and picturesque hiking trails. The 10,000-foot Haleakala volcano has terrific lunar-landscape trails for walkers and the Hana Highway is ranked as the most spectacular coastal drive in Hawaii. The main attractions on Hawaii, "The Big Island", include the spectacular Waipio Valley, the Hawaiian Volcanoes National Park and Puuhonua O Honaunau National Historical Park, which is full of ancient temples, royal grounds and ancient burial sites.
It's great to do a bit of island hopping and Kauai, "The Garden Isle", should be on your island hit-list. As the name would suggest, the lush green countryside is stunning and places of interest include the 22 miles of coastal cliffs on the Na Pali Coast, along which you'll find a spectacular trail and the Waimea Canyon - the "Grand Canyon of the Pacific".
Molokai is the most traditional Hawaiian island, where there's little sign of development and mass tourism. It's a place where you can enjoy quiet hikes in the rainforest, and it's also home to the world's highest sea cliffs in the wilderness area on the North Shore. Finally, if you really want to get away from it all, Lanai, once a pineapple plantation, is very small and extremely exclusive, and has only one town.