Kinda depends on your priorities. I would like lower deck (less motion, and getting off and on the sip several times in port is convenient, as others pointed out). It's nice to get back from the beach, change quickly, then go into town and shop. Never underestimate the time to walk to the high back of the ship on those days
But, if you are an avid pool fan, don't care about noise and motion, and want to jet into your cabin often on sea days, you might want an upper deck room.
And if you like to snack several times a day instead of eating big meals, its convenient to be on the same side of the ship as the buffet (front or back) so the stairs are easily accessable.
If you are sensitive to noise, book something with cabins above and below and away from stairs and elevators. If you sleep like the dead, don't care about noise, motion or location, save money by booking a guar.
Lots of ways to do it
