Even as a grizzled old Navy man I can have moments of motion sickness, although not severe. I do recall having to leave dinner on the Carnival Legend in 2005 because of the motion and going back to the cabin and laying down. Of course on that cruise we had an aft-facing balcony and we got to feel lots of the pitching, so laying down didn't help much but after a while I was back in fighting form. I do know I was happy to see our next port.
I had a studio cabin on the Norwegian Getaway last week and even though I am claustrophobic I was fine. They are nice cabins for the single cruiser. BTW, Billy, if you are going on Getaway you will like it. Great ship and crew.