i'm a transplanted hawaii guy (born and raised in honolulu, HK!) so here goes some suggestions, for oahu:
In no particular order, just off the top:
1. rainbow's drive in on kapahulu ave. - you must eat boneless chicken plate lunch and wash it down with a slush float.
2. swap meet @ aloha stadium - good for cheap trinkets to give for gifts, lots of cheap stuff
3. ala moana shopping center - hot girls and decent shopping
4. ala moana beach park / magic island
5. chinaman's hat
6. snorkel at hanauma bay
7. check out waves at north shore (better in winter time when its huge)
8. drive around the island, check out west side
9. dole plantation tour
10. diamond head hike
11. waiola's shave ice afterwards on kapahulu ave.
12. polynesian cultural center if you want to be the ultar tourist
13. go to pali lookout and almost get blown off the edge while seeing dope views.
14. rent kayak and go out to kailua beach park and kayak
15. check out drift session at hawaii raceway park
16. go see what kinda prices they charge for peformance parts at certain shops out there
17. go clubbing, don't get beat up, check out the local wimmens
18. eat bacon avocado burger at kuaaina big burger, in haleiwa or at ward warehouse in town
19. take surf lessons at waikiki
20. eat at zippy's resturant...the chili is a must
that's off the top of the dome, there's much more you can see and do in hawaii, just try to find out what locals do and do that, touristy stuff is overrated.
and if you're not going to oahu, then crap, i just wasted 5 minutes.
