There are several cruise lines that do world cruises, Princess and Cunard are two that come to mind. You could probably get a partial segment. Princess does sometimes reposition ships and does Tahiti to Australia, which you might be able to add Hawaii to Tahiti to. I'm sure a travel agent would be a very valuable asset for this type of cruise.
You can never predict what seas will be like, could be smooth as silk or rougher than sandpaper. You will feel more motion in smaller ships, there's no doubt about that.
It sounds like a wonderful way to celebrate retirement to me. Heck, go for the world cruise, it's only a couple more months
Your Allure cruise is coming up shortly, here's wishing for sunshine, calm seas, great food, and an amazing cruise!!