When I was there we listened to Krater 96 in the car all the time, which is top 40 from the 80s, 90s, and today. I listen to it at home frequently which is cool because you get the Honolulu traffic reports, news, weather, so it feels like you're there.
http://krater96.com/
Also if you want to hear some contemporary Hawaiian music then local favourite John Cruz has his music played on radio stations, malls, airports, hotels, and just about everywhere on a daily basis, especially his biggest hit from 1997 'Island Style'. Anyone that has been to Hawaii in recent years will know this song off the bat.
video of Cruz singing Island Style -
http://www.youtube.com/watch?v=07SrFYQDiAE
Icepick - Does it ever occur to you that you are always having to bail your friend Magnum out of trouble?