My husband has cruised on Princess once before (about 12 years ago) and he really wanted to go with them again. I wanted to be able to drive to the departure port so we chose a 7-day California Coastal, round trip from LA. It was just the two of us ages 45 and 46. Left the kids at home since they don't appreciate cruising (which is fine with me as it's much cheaper that way!).
After reading many reviews on the aft balconies, I chose cabin B754 which we loved. We did get some movement when we were out at sea but we found it soothing. I chose Baja deck so we would be neither above or below any public areas and it was nice and quiet. Sometimes we did hear "ship sounds" but nothing that was ever a problem.
The cabin was adequate and the balcony was larger than I expected, which was a nice surprise. It had two chairs and a small table. We didn't use it for dining or anything- just sat in the chairs (or more frequently, stood at the railing) and enjoyed the ocean. The shower is miniscule! I understand this is the norm on Princess.
Balcony bigger than I expected (not sure if all aft balconies are like this as I have no frame of reference. Tiny shower. The bed and pillows were comfortable to us. Did I mention the tiny shower?
Nothing really to do except buy lunch.