We went to Hawaii for 1 week earlier this year. Stayed 3 nights at Sheraton Maui and 4 nights at Sheraton Waikiki (on Oahu of course).
Deka is definitely right...Waikiki is pretty much just like Surfers Paradise, except the actual Waikiki beach is pretty coughpy (very rocky, tiny waves and very narrow sand part of beach. We didn't really like Waikiki or Honolulu all that much and when we go back will probably just stay there for a day to do some shopping at the factory outlets and Ala Moana Mall (cheap for us Aussies). The Sheraton was great and we would probably stay there next time....seems to be one of the better and most modern places along the strip, but doesn't has its very own beach right off the back of the hotel like many of the others (however they make up for this with an infinity pool).
Maui was fantastic and I would be telling everyone going to Hawaii that is is well worth the 45 min flight from Honolulu. Is a lot quieter than Honolulu and Waikiki, which makes it very relaxing. Have a big strip of resorts which all have great beaches at the rear, some great scenery and places to see. Beaches are much better than Waikiki and from the Sheraton you can just snorkel 100m off the beach amongst heaps of tropical fish! We loved it at Maui and will be the place we go back to and spend most of our time there. Sheraton Maui was great and whilst not cheap, was well worth it. One thing to keep in mind is that the resorts are about 45 min drive from the airport - in hindsight we probably would have hired a car and driven ourselves if we knew that it would be an $85 taxi ride each way, the roads relatively quiet for us who are used to driving on the left side of the road, and most resorts providing car parking included in the price.
Good luck with it...lm sure you will enjoy your trip.