My choice between decks at least would be the 10, you'd have cabins both above and below, so no chance of some public area either above or below. If you are prone to motion sickness, then midship is good, don't think it matters which side on the deck.
On our Northbound Spirit cruise to Alaska we had room 7155 on the Verandah deck. It was on the starboard side of the ship. It was toward the front but we didn't notice a difference between other rooms. We liked it because it was the highest deck you could be on while still having staterooms above and below. It was also nice because with the odd shape of the side of the ship, it was on a corner and we had a good view looking aft.
Holiday Baja Mexico 8/98
Disney Wonder Bahamas 8/00
Ecstasy Baja Mexico 8/02
Carnival Spirit Alaska 7/03
Ecstasy Baja Mexico 8/03
Adventure of the Seas Southern Caribbean 12/04
Carnival Pride Mexican Riviera 8/05
I like the back corners. Sometimes you can find one with an extra large balcony and that makes all the difference. They get more protection from the wind making them usable for the whole trip. some other aft and midship room are too cold or windy to use the balcony much.
On ships this big, I didn't notice a whole lot of difference where you were when it comes to movement and rolling.