FWIW, I got quite lucky today between an absolutely exceptional crew (which I don't say lightly) and a half empty rear cabin.

I selected 96A when the bulkheads opened. During boarding, crew proactively informed me that 96D was empty and asked if I would like to move, as 96D doesn't restrict you to the cubby hole. As a window watcher, I declined (I had made the choice for A over D when selecting my seat originally), but was appreciative that they thought to ask. I overheard them offer the same choice to at least one other person further up the cabin, but evidently nobody took the offer.

Once in the air, FA came by again and offerred to turn down 96D as my bed so I could stick to just eating and lounging in 96A. This was the first time I can recall crew offering to turn down a seat dedicated as your bed and let you have another for everything else. I've certainly had this in F (e.g., LH, CX) but not in J on SQ or any others (e.g., JL, CX, BR, EY, OZ, LX, AC, UA, GF, TG, HU, QH, etc).

There was someone in 96F, but given the privacy divider, an empty 97A, the combined space of 96A and 96D, and the privacy of the rear cabin in general, the amount of space and privacy could rival F.
To top it off, every time I switched between laying down in the bed and going back to my original seat to watch shows or work or eat, the crew always re-made the bed.

Long story short, while it can be hard to weigh a preference for the window part of the window bulkheads against the preference for a better sleeping experience, in rare cases you may get lucky and get both. And if debating between 96A vs 96K, you may want to select the one adjacent an empty middle, if available. That may require checking the seat map up to the last minute.