I found on my first cruise (on the Sensation in 2000) that how much you feel the motion depends on your deck. All of the couples at my table had cabins on the Riviera deck but one...the couple who had paid more and ended up on the Empress also were nauseated for three days of the trip while the rest of us below were OK. Could have been coincidence, but it seemed to me the motion of the ship was much more discernable when I was in the dining room or on the Lido deck then it was down in our cabin. And even then it wasn't that bad, except for the night we went up the Mississippi River to New Orleans. 100 miles of twisty, turny river in a HUGE ship made for some interesting sharp turns! : )
I also found the wrist bands at CVS, so most drug stores should have them.