Best Hawaiian vacation islands?

[Jeph]

I'm doing a wish for Make A Wish and I wished (and it's granted) to go on a vacation to Hawaii. I am limited to one Hawaiian island for a week. I have 3 younger siblings (ages range from 9-13, I'm 15) and an older sister (18) along with two parents. I was wondering if there are any recommendations for what island I should go to, and why.

What are the best and worst things on each island? We don't want to regret picking the wrong island! What were some highlights of your vacation? What about the things you don't recommend, or recommend not doing? Just wondering, trying to pick the best island for the most memorable trip. Thanks a ton!!

We definitely want to swim, and site see somewhat. We've never been to any island of Hawaii so we don't really know WHAT there is to do exactly. Any unique or interesting things that are MUST do's?

 

[AHunch]

If you want a lot of different activities Oahu would be the best option:

 

[FrankCastle]

I'm from the Big Island, although I lived on Oahu for many years. I think Kona is really nice, its on the west side of the Big Island. Hilo is on the other side. Do not come to Hilo. There aren't really good beaches here and sometimes it can rain a lot. There's not much do. It's not that bad, but it's not that great either. Kona's really nice, it's sunny, and there are better beaches for snorkeling. Kona town is a nice place to walk and see sunsets, and there are good places to eat. Kona's more of a relaxing place to go and snorkel, but not so much action, which can be a good thing.
Honolulu and Oahu have more action, but with more "action" comes traffic, crime, overdevelopment. Honolulu is a big city, and a lot of people don't really realize that before they leave there. Waikiki is a pretty busy place on the beach, but there's lots to do within walking distance. Hanauma Bay is a must in my opinion if you go to Honolulu, as its a great snorkeling area.
So in general, I recommend Kona on the Big Island. If you go to Waikiki, on Oahu, I would just stay in Waikiki or else you have to deal with traffic. But that's just my opinion.