All the cabins on the stern of the Millie Class ships are terrific cabins. You may want to bypass those immediately under the aft outside bar area because of the "noise" from the evening entertainer there. But other than that, the rest in my view are the most desirable on the ship.
If you really want to be spoiled, and can get one, take a look at the corner Category FV cabins.
We cruise every year and last year was the first time we had the rear of the ship and loved it! The lower the floor you are on the larger your balcony, due to the fact it is tiered. Our balcony was about the same size as the room. We never felt the engines or heard the noise from the back bar which was several floors up. The rear bar is used mostly at lunch and sunset cocktails so it never created any problem for us.
We have the Summit booked for a stern room and I'm now looking at next years cruise. We have always enjoyed staying as high up as possible, but it may be worth staying on the 6 or 7 floor if the deck is bigger than 8,9,10....