Have you been to Hawaii before? Honestly we were there just under 2 weeks and wished we had more time and that was just on Oahu. I thought we are flying all that way we should take the kids to another island but dh said he wanted to park it. I was happy he did.
There was so much we did not see and do on Oahu yet we did so much. It really is the perfect place for those who love adventure and want to relax in beautiful scenery as well. We went to Diamond head, Hanuama bay snorkel, Kualoa ranch, Dole plantation, Waikiki, Makua beach and west side, Sharks cove snorkeling, Halewia, Turtle beach, Lanikai beach, paddle boarding. We ate at all the hot spots for food like saved ices and garlic shrimp trucks, Taneokas (a must) Leanords etc. and spent time soaking up Aulani and Ko Olina. We still missed so much I wanted to do. Polynesian cultural center, Bishop Museum, Surf on Waikiki, Pearl Harbor, some unique hiking spots etc. Long story short you could fill tons of time there. If you do go to another island my sister loves Kauai for the nature and hiking and the big island for the country feel and beaches. We have only done Maui and in my personal opinion while beautiful and has great resorts it skews for honeymooners and was glad we took the kids to just Oahu. Just my take!