It's quite simple: Hawaii is part of the United States, where residents speak English, the currency is US dollar and you don't have to worry about drinking the water...haha!
This naturally makes wedding planning much easier, as you'll know what to expect. Communications with all vendors will be in the same language and there is much less room for error or confusion due to a language barrier. Plus, you'll find the same excellent standard of service, may it be in services rendered for your wedding or hotel accommodations, that you've come to be accustomed to living in the US.
You'll greatly reduce the chance of a wedding fiasco going with a destination wedding in the United States.