ALoha Bobbi,
What port are you leaving? I fly out on Tuesday to catch the Wonder returning from Hawaii. They have had a lot of passing storms lately, but I don't expect it will remain that way. This will be my first trip to Hawaii in Sept, but I did do the 14 nt RT on the Wonder in Oct, 2012. We left out of Los Angeles that time and we had some rough seas for the first couple of days. When I say "rough" they really weren't bad at all IMO. Just some waves and chilly weather from LA. Once we got within a day or so of Hawaii, I swear everything changed, the seas were much calmer, the light was prettier, it was awesome! Hopefully it will be the same for you. Our cruise will return to Vancouver, BC the end of the month.
Have a wonderful cruise!!