If you're on Oahu, I can help out.
I go to Island Triathalon and Bike for service and sales. I got a thousand dollar bike from them in august and haven't paid a cent after that (except for tubes) for the many adjustments that my riding necessitates. They're mostly geared toward triatheletes and racers, but they'll help you out with all the advice and knowledge you can handle even if you aren't doing the Iron Man.
They'll let you take out the bikes and they're there to make your bicycling as fun as possible. But if you're after specialized or giant, they're not the place to go.
McCully Bikes on King Street is alright once they treat you like a human and not a sale, and they deal in Giant. The Bike Shop on King is also great, and they sell Specialized. If you're moving to Kailua or the windward side, they've got a shop there, too.

As a matter of fact, they're all good, except for the one in Kakaako. They don't treat you with respect unless you're pro or semi-pro, and the management doesn't seem willing to let the sales staff spend too much time with questions and advice. Just my experience and word of mouth. I got a Trek from the shop in Kakaako and it just never ran right, and they made me feel like a total putz whenever I asked for advice.

Good luck and welcome to the islands.