Vacationers flying to Hawaii are often surprised to learn that their plane lands in Honolulu (on the island of Oahu) and not the Big Island of Hawaii. We Mainlanders call the whole island chain "Hawaii," not distinguishing between the different islands - even though each island is uniquely different in culture, size, and experience. I used to live in Honolulu, a busy city of like a million people spread out into different districts. I feel sorry for the thousands of overworked tourists who spend their hard-earned money to fly over to Honolulu seeking relaxation and uncrowded beaches and end up befuddled in this busy city.
Don't get me wrong - Oahu is one of the most beautiful places on earth. But chances are, if you're a tourist, you got sucked into staying at a Waikiki hotel with no idea what to do or where to go. You'll end up unhappy, stuck on the strip, dining at TGI Fridays with the other unfortunate suckers. Plus, Waikiki has a party atmosphere - good for showing off your new breast implants - but definitely not relaxing or kid-friendly. If you are flying to Hawaii with your girlfriends to hook up with some guys and have a one night stand, then Waikiki is for you. But if you are flying to Hawaii with your hubby and kids because you want a relaxing week away from your job and envision yourself sitting on a deserted beach with a glass of wine, do NOT stay in Waikiki. It's like the Miami Beach of the Hawaiian islands.
I recommend flying from Honolulu to Big Island if you envision yourself swimming in the ocean or barbequeing with your family at the beach. (If you do stay on Oahu, stay on North Shore and get a good local guidebook that tells you where all the good hikes are - the hiking on Oahu is incredible).
Big Island is way more family-friendly than Oahu. Fly into the Kona airport (not the Hilo airport). Hilo is the rainiest city in the U.S., while Kona (and Kohola, both on the west side of the island) get only like 10 inches of rain a year. One caveat - this side of the island is covered with lava and not as "tropical paradise" as you first expect. Don't let this throw you - the beaches here are AMAZING and astonishingly beautiful. If you crave a "rainforesty" hike, you can always drive 2 hours across the island to Hilo (where the rain creates plenty of rainforests and breathtaking waterfalls and cool caves).
I recommend staying on the island for at least two weeks. The actual island of Hawaii is bigger than all the other islands in this chain put together and there is plenty of stuff to do here. If you have just one week and relaxation is your goal, rent a room at a resort on the Kohala coast. This way, you will be guaranteed to have a beautiful white sand beach within steps of your room. If you stay in the town of Kailua-Kona (where I live), you will find lava rock beaches that are not accessible to non-swimmers. If you do stay in Kailua, bring some felt-bottom reef shoes. The only problem with staying in Kohala (a region not an actual town) is that you will be too far north to drive to Volcano National Park and back in one day.
You will need a rental vehicle if you stay here. Guidebooks will tell you to get a 4 wheel drive (like a jeep) but that's not necessary unless you plan to travel certain roads. In my opinion, the biggest reason tourists don't have a good time is they try to do too much in too short a time. The most fun thing to do here is to just hang out at the beach. If you don't like the beach, go somewhere else. The shopping is way better on Oahu.
If you want to enjoy yourself here - it's simple. Bring sunscreen, two bathing suits, a snorkel and mask, reef shoes, and your debit card. Don't bother with boogie boards, surf boards, or other expensive gear. Trust me boogie boarding takes a couple weeks to become good at anyway. There is a Target and a Walmart here so you don't really have to bring the snorkel with you.
Consult my other blogs for advice about the best beaches to swim and snorkel on Big Island. (And please feel free to email me if you're here and have no idea where to go. The best destinations are off of easy-to-miss, unmarked gravel roads that no one else will tell you about). I sincerely want you and your kids to have a relaxing, good time here. Have fun!