we went in april and just a word of advise, don't arrive too early, after you get your lei at the start, they lead you to a waiting area, and it gets very hot very fast, with few places to sit.
we wore hawaiin garb of course!!! i bought hubby a hawaiian shirt, much to his dismay....i got a flowy sundress from old navy that had flowers all over it....ds had a hawaian shirt from the childrens place that i got for like 2 bucks at an outlet, and dd a set from costco that had a basic tank and big outlines of flowers on the skirt. she loved it to pieces. i was totally going for that cheesy look. but we didn't look half bad! lol we were going to go in feb, but i figured it would be too cold....enjoy!