Since each island has its own personality it's really a matter of preference and you need to sort of research what you want to DO on each island. We have stayed on Oahu, Maui and the Big Island and did a "day trip" to Kauai once. The time we went to Kauai we went from Oahu VERY EARLY, rented a car for the day and just drove around. We visited the Mauna Loa macadamia nut plantation/factory, hiked into the rain forest for awhile and drove part way around Waimea Canyon before we decided we'd best head back to the airport to catch the last flight back to Oahu. You can totally lose track of time. Kauai is beautiful but we didn't feel that we found as much to do there to warrant going back to spend the night although I suppose we SHOULD at some point. Waimea Canyon is like going to the Grand Canyon - it's beautiful but it's the same scenery for miles and miles. We felt Kauai was more of a honeymooners type quiet. So if you like to hike or if you're looking for a relaxing do nothing but lounge around kind of island I would suggest Kauai.
We also did a day trip to the Big Island once from Oahu before we had our son (staying at like an Outrigger Hotel in Waikiki is usually the cheapest option of any of the islands so that's why we did our day trips from Oahu when we did them). That time we flew into the Hilo side and we rented a car for the day and drove to both Akaka Falls State Park and then down to the southern coast to visit a black sand beach and swim with the sea turtles (VERY COOL BTW). We had booked a quick helicopter tour for the afternoon that just flew over the active volcano, Kilauea. (If you do just a day trip try to utilize and minimize the time spent at the airport for either early or late in the day if you book a helicopter type tour.) We soon realized that the Big Island truely IS big and that there was no way to see it all in a day so then we planned to go back to spend a few nights on another trip. So on our LAST visit to Hawaii we went to the Kona side and spent 3 nights. We did another helicopter tour - a longer one that flew over the volcano (I cannot stress just HOW COOL that is) and then up around the northern Kohala Coast to see the waterfalls. We did a LOT of driving on that trip for just general sightseeing and we brought our snorkeling gear and did some off-shore snorkeling (which was THE BEST EVER) on the Kona side. We still haven't seen everything on the Big Island. They really don't have good beaches on this island if you're a beach fantatic. As this is the youngest island the coast is covered with black volcanic rock - so there are not a lot of natural sandy beaches. If you're looking for super gorgeous beaches then you want to be sure to visit Maui!!
Maui is our favorite. There is a lot to do there. I have visited Maui on every trip. I have stayed in Ka'anapali 3 times and in Wailea 1 time (I think Wailea tends to be a little pricier to stay). My first time to Maui I did a day trip on a catamaran to the little island of Lanai which was very relaxing. It's really just a beach kind of day. We always book a snorkeling trip from Maui. There are a lot to choose from out of Lahaina or Makena. I have done the drive to Hana 2 or 3 times (I forget now how many). The last time we did not go up to Haleakala for sunrise bcuz we had our son with us and it didn't seem like a good plan to get him up at 2:00 am at that time but I want to do that again next time. It is simply AMAZING to see the sunrise from above the clouds. (This is not something you could do from a cruise.) What time you have to get up to make the long drive depends on what time sunrise is when you go. But it's about a 2.5 hour drive depending on where you're staying I think so if the sun comes up at 5:30 when you're there then you'll want to get up at like 2-2:30 to get dressed (WARMLY) and to head out. It is VERY cold up there. You don't want to be late & miss it so plan ahead. Since we're usually pretty wiped out that day we don't usually plan anything else for the rest of the day other than lounging by the pool / beach & napping.

A lot of people who like to bike book a bike down Haleakala tour. They go up in a van then ride back down on bikes. Maui has lots to see and do so we like to spend at LEAST 4 nights there.
Oahu is our least favorite & we usually only spend 2 or 3 nights there before we move on. With Aulani though I figure we'll give it a try for 4 or 5 nights. Since we're using points it will be the cheapest stay for sure. I went to the Polynesian Cultural Center on my first trip and it was a long day. I haven't had the desire to return, although if we drove ourselves it might be better 'cuz we could leave whenever we wanted. The time I went I was on a bus with a tour group. And I was STUCK there. We left very early in the morning and didn't get back to our hotel until like 11:00 that night - it is on the opposite side of the island from Waikiki. Personally, I was done with it by like lunchtime, although they DO put on a very nice show at night. We usually go snorkeling at Hanauma Bay and we ALWAYS, ALWAYS visit Pearl Harbor. Last time the USS Missouri was there so we toured that too which was cool. Pearl Harbor is probably why I always insist on visiting Oahu. I find it fascinating and just can't miss it, ever. It is one of the most moving experiences you can ever do. Having seen / done the Punchbowl I don't feel the need to ever go there again either.
Depending on the time of year you go you will probably want to try to go on a whale watching type excursion (best probably January - April).
Golf - if you golf you should plan to golf on one of the islands. I would recommend doing that on Maui or the Big Island probably. I personally don't golf but I surprised DH with a round on Maui once. It was the time we stayed in Wailea. I arranged it thru the concierge at the hotel we stayed at. Rented clubs & got the tee time all set up and he played on the course where the Gold Masters play. I went along for the ride / day and he was paired up with another couple. It was an amazing course. Very difficult for him because he doesn't golf a whole lot but it was just something fun for him to do once. The course ran along the coast and had some amazing views and old lava fields as obstacles etc. The couple that he golfed with were BIG golfers and they were literally golfing someplace different every single day!!
Island hopping can be a little time consuming. I would recommend going early. Get your rental car and get going. Just looking real quick on Kayak.com I see flight prices from HNL to KOA (Kona) are about $77 one-way and they are 43 minutes. Prices from HNL to OGG (Maui) are $73 one-way and are only 37 minutes. Flights from OGG to KOA are anywhere from $76 - $110 and would be a little longer (just under an hour I think). I saw some odd ball airlines listed that I am not familiar with (Mokulele and Pacific Wings to name a couple). I would probably research those a little bit before booking them but they are super short flights so I can't imagine they could be THAT BAD. You just want to make sure your luggage gets there with you if you're transferring islands. But you are literally up and then down on these flights.
Do a little research on the types of activities you like to so whether it's golf or snorkeling or historical / educational type stuff so you can make an informed plan. Rental cars are a MUST so budget for those too. There is no way to fully understand just how much there is to see and do in Hawaii until you actually GO there. If you are going for at least 2 weeks I would recommend trying to change islands 3 times. Last time we went was the first and only time we took our son but we only did 9 nights / 10 days. So we did 2 nights on Oahu (so we could take him to Pearl Harbor) then 3 nights on the Big Island and 4 nights on Maui. We found it to be a little too hectic of a trip. We should've planned for a couple more days to do 3 islands but we really wanted to take our son to see the volcano on the Big Island. In the future if we're only there for 10 nights like we will be on our next trip then I will limit us to 2 islands. It's too much packing & moving otherwise. But 2 full weeks is enough time I think to see 3 islands - while 2 or 3 nights is too rushed we feel 4-5 nights on each is adequate and want to move on.