We did a 28 night Caribbean with P&O.
We had about 8 formal, I took two pairs of trousers (just in case really) one white jacket & one black jacket, two shirts but then P&O have a S/S laundry. My wife took about 6 dresses. we tried to cut back on shoes for weight. Out of interest, one lady at our table who always looked wonderful, I asked her if she had brought 28 dresses, she said nope I brought 33 so I had a choice!!
We both loved the sea days, I find little of interest to me on ships during the day but I find just relaxing suits me, either on deck (beds hard to find), or on the balcony (aft overlooking the wake..worth every penny used it a LOT).
Not seeing land did not bother us & never thought of it.