! Imaui or Oahu Best with Kids?

LOVE Hawaii!!!
I've been to Maui twice (Westin Kaanipali and a condo at Napili) Kauai once (Poipu Beach) the big island once (Kona Village) and we just went to Oahu right before Christmas, we stayed at the Royal Hawaii'n.
It really depends on the age of your kids and what you all like to do as a family. I like Maui a lot but to me it's too much like California, lots of strip malls, hotels and chain restaurants, so personally it doesn't feel all that exotic. Though if you go there you MUST have a meal at Mama's Fish House :)
Our kids are teenagers now so Oahu was a BLAST! Yes, Waikiki is a city (complete with office buildings, fancy stores and restaurants) but there's also a lot of history there. The Royal Hawaii'n Hotel is one of the very first resorts built in Hawaii and it is to die for. We loved visiting Pearl Harbor and snorkeling at Hanamua Bay.
My personal favorite island with little kids is Kauai. It is really laid back and feels very much like old Hawaii, hardly any big shopping areas, chickens running wild. It's like the countryside of the islands, beautiful and relaxing.
No matter what you decide it will all be good, I think it's impossible to have a bad time there!!!

Then I would opt for Maui.

Go to their tourism website and some ideas:
http://www.gohawaii.com/maui
http://www.nps.gov/hale/index.htm
http://www.tripadvisor.com/Attractions-g29220-Activities-...
http://www.tripadvisor.com/Attraction_Review-g60633-d###-...

Then you can plan your activities.

Us locals, refer to the outer islands as "country." And Oahu is the "city."
But there are many activities on all islands.
There are "luaus" & hula shows offered on most all of the islands.
Research it.

Waikiki is expensive. It is a tourist destination.
Hawaii is just an expensive place and expenses will vary on which town you are in and what you are eating/buying.

As far as lodging and airfares, you have to research that.
And peak times, are generally more expensive.

Maui, is more "hawaii" like.
Less citified, less traffic, more relaxing and calmer.

Maui is great with kids. The Westin Kaanapali is a fabulous resort. If you have a big budget, the Grand Wailea is truly amazing and the kids would have a blast. Maui has an aquarium you can go to with the kids and they will be happy just playing on the beach and pool. You could rent bikes one day if they are old enough for that.

If you end up choosing Oahu, you can stay at the new Disney Aiulani resort. It's not in Waikiki.

I'd choose Maui. We brought our kids there last spring and had a great time!!
I also love Kauai, that is where I got married! I enjoyed Oahu, but I prefer the other islands for my vacations.

When we go to HI, we stay on Oahu. We rent a house on the beach in Kailua, which is much more laid back than Honolulu, but we can still get to town within about 20 minutes or so. I've been to the other islands, which were nice and beautiful, of course. But I remember being really bored there (especially as a kid). We usually go to HI for the entire month of August, so we like to be near a big city for all its amenities and activities.

I have been to both islands and personally loved Maui the best. Oahu does have many activities, but Maui is more laid back. For this reason I would choose Maui. There is a lot of nature related activities to do in Maui. Oahu is nice, but quite crowded.