Haven't read all of the replies - just tossing in what I know.
Only been sick on one cruise with bad weather. I tried the wrist bands but eventually bought the motion sickness pills from the ship (assuming it was something like Dramamine.) That worked really well for me.
I'd bring a mix of what's been suggested here. You can try the easier things first and move up if necessary. Doesn't take up much room and armed with all that stuff you should feel comfortable that you have options and not have to stress about it! NO STRESS on vacation!!!!