I heard that there's actually a small Yoshinkan club at the University of Hawaii Manoa that started up recently, but I don't know much about them. There hasn't been much Yoshinkan activity in Hawaii since Yukio Noguchi passed away.
Pearl City (Donald Moriyama) is a good club, and so is Mililani (Dennis Oka). I train at The Aikido Ohana
,which I like, of course, and there is a fairly comprehensive list of Hawaiian Aikido dojo on the Aikido Hawaii