On the topic of weather -- not to dispute other posters, but I lived in Mililani (central Oahu) for several years, and your chances of getting rained on in January and February are very good indeed. It is not out of the realm of possibility to get an entire vacation week rained out during that period. In pidgin, "you get one big chance rain den, braddah."

When folks ask me the best times to visit Hawaii, I tell them October and April-May. October is great because the tourists have generally all gone home, and because the locals are either back in school or back at work, depending on their age. In April/May, the tourists haven't showed up yet, and the locals, with that marvelous Island "manana" attitude that I call "Polynesian Paralysis," haven't stirred up enough energy to descend on the beaches yet.

Weather is particularly warm in October, and I'd recommend that month to anyone planning a trip to the Sandwich Islands.

Whatever you decide, enjoy!