There's all kinds of Hawaiian music and I'm wondering if you're looking for general suggestions or a specific type?
However, for my personal tastes, I concur with Dan's suggestion on Israel Kamakawiwoole, some of his music has been in movies and tv shows (ER is one), and is really beautiful. He used to be in a group called Makaha Sons.
Anything by Na Leo Pilimehana (they often go by just Na Leo these days) is a good bet too.
Brothers Cazimero, but their music is not as main stream as Iz and Na Leo.
For some slightly older stuff, the Krush and Kalapana (those are groups that are no longer together). Also, Audy Kimura for a mellower sound.
I like Kapena too.
Cecilio and Kapono (commonly referred to as C&K) is very popular.
If you like instrumental stuff, Jake Shimabukuro is a terrific ukulele player.