Will our iPhones work in Hawaii with our regular phone plans or do we need some version of an "international plan" (and yes I realize it is not international---but something different than the regular plan for the continental US?
I agree. We have been many times and haven't had issues with AT&T except Waimea Valley ( although I've been able to get connected before crossing the road to Waimea Bay). We've also traveled with friends with T-Mobile. I think all the major carriers have Hawaii maps on there websites, so you can see your coverage. No roaming charges for us on AT&T or friends on T-Mobile.Don't need a special plan.
FYI, I have AT&T and have had pretty good service around the island, except for Waimea Valley.
Also, the Wifi around Aulani is pretty spotty. So if you consume a bunch of data, you may not be able to rely on the Aulani wifi.