@CanadianBride456: So here is my synopsis of the various islands.
The Big Island:
This is major volcano territory. I haven’t been there since I was 13, but if you want live active volcano’s, this is where you go. I know it has a lot more to offer I just can’t speak to it much at this point. Oh, and they have a manatee scuba dive/snorkel there that is on my bucket list. Probably number 3 even though i don’t remember a lot
Kauai is extremely laid back. It’s very much about hiking and outdoor activityes. It has Hanalei bay which is totally hippie town but adorable and fun. It doesn’ thave the long stretches of white sand beaches that some other islands do but it does have plenty of beaches and white sand. When we were there, we definitely needed a car, and night life, restaurants, etc were pretty hard to come by. And we definitely needed a car to get to any beaches frmo where we stayed. It’s a jungle island really so it doesn’t get quite as much sun as other islands. If you are into nature, hiking, outdoors, with a bit of relaxing, and being kind of isolated, Kauai is your bet. We had a fabulous time here but its not my number 1, probably number 2.
Waikiki is extremely “happenin”. It’s like vegas on the beach. It doesn’t have as many activities as some of the other islands but there is of course the major shopping, a TON of active night life, long stretches of very busy beaches, the North Shore, and Pearl Harbor. It’s a pretty flat island. We spent 4 days there and that was enough. But if you crave night life and want to relax on the beach all day and go out at night and do major shopping and meet people etc, this is a great spot. It’s my number 4
By far my favorite island. We actually just went in February. There are multiple area’s on Maui that you can stay, Ka’anapali is a popular area, and down in the Makena/Kihei area as well. There are long stretches of white sand beaches, WE did the road to Hana in a jeep and loved it, little towns here and there that you can stop in, shop, etc… Boogie boarding, surfing, diving, turtles etc… Also a day trip to Lahaina is really fun for more of a touristy cute town feel and they have quite a bit of shopping and restaurants. Definitely my number 1 choice, especially for those who don’t make it to hawaii a lot and don’t see themselves having the opportunity to go back soon.
Another thing: The islands are very cheap to jump between and only 30 minute flights, so it’s completely feasible to do part of your trip on one island and part on another. When we did Kauai we stayed there for a week, then went to Oahu for 4 days over 4th of July (which is where we got engaged, in 2011 ;))
ETA: I’m happy to give you more specifics about the things we did on each island if you want to know, but as a start an overview is good!