I'm guessing you mean a good Oahu guidebook? I've heard the "revealed" ones are good. Also check out some Hawaii message boards. I like the TUG boards (Timeshare Users Group).
Also some Hawaii website like Visit Oahu, but they're more adverts for touristy things.
If you need any money saving tips, just ask me. I go there every other year, and my son was born on Oahu when we were stationed there. We tend to do a couple touristy things that are traditions, like visit the Dole plantation and the swap meet at the stadium. We eat out for lunch if we're out and about, but cook in (we stay two weeks at the Marriott next to Aulani - next year I have 4 weeks booked though). We like more local places, but have been known to do carry out from Panda Express in Kapolei, LOL.