OGG (Maui) rental this fall, 5+ days (weekly rate), base rates:
disc code compact intermed.
Orbitz $182+ $193+
A074800 (citi) $165+ $170+
B292100 (dcbar) $177+ $188+
C031529 $177+ $188+
B999900 $177+ $188+
K019300 $187+ $198+
The last one is a United "promo" that purportedly saves up to 25%. That's almost a fraudulent advert, as it is higher than the orbitz rate!
Avis.com is showing a nice $30 off one-week promo (valid 8/20-12/15/07) but it is limited to continental US

- use code MUWA086
Thanks again to whoever first posted the citi rate.
And feel free to use the DC Bar rate, nobody has ever asked for my membership card.
Addendum: After all this work I find out I have to book my car througha special rez # and Avis will not let me use any discount codes with my Hawaii voucher. Aargh!