WTP is my preferred cabin for cost vs comfort. I feel much less cramped in WTP (and I'm only 5' 5"). The seats are broadly equivalent to American carriers' domestic first or to international business class about twenty years ago before the rise of flat-beds.

Another advantage of WTP is that it's the smallest upgradeable cabin so the chances of op-ups at busy periods are higher. Last autumn I scored a run of op-ups from WTP to CW and I've seen stories here of flights where WT has been so oversold virtually all of WTP got op-uped.

That said, I would agree that there is a limit to how much extra I'd pay for WTP - typically when I've flown JFK-LHR I've paid up to $300 a sector extra for WTP and thought it worth it, and as I was tending to fly at fairly short notice last year, I sometimes found flights where WTP was cheaper than WT!

If you do decide to go for WT I would agree a window or aisle seat, especially at the very back of some aircraft where there are only window-aisle pairs helps make the experience better, and buying the premium WT meal where available brings you pretty close to the WTP experience.