Ahh, Oahu. Probably the worst of the places I went to in Hawaii...the only good thing was Pearl Harbor really. I didn't even like Waikiki that much (the water was murky, the rocks at the bottom are killer, beach isn't free). See if your parents can detour to Maui, the best island in Hawaii. All the beaches are clean (except one along the western coast, forgot what it was called) and free, they have TONS of stuff to do, and the weather is great. Scuba diving was awesome (first time I've ever dived, and I went twice in two days ) snorkeling is fun, dunno how to surf , and the island is beautiful. We went on the Hana drive, which took all day and looked really awesome, it takes you to the back of the island where a lot of small beaches are located. We went to a pineapple farm (where I found out that I was allergic to pineapples...) which was fun, although it's hard to believe. Our hotel, the Grand Walea is amazing, a lot of it is outdoors and it's right up against the beach. I'd have to say it was probably the best vacation I ever took.
Sorry I can't say much about Oahu, we only spent a day and a half there, but congrats with your graduation and have fun!