In WTP there is a solid edge to the seats, and a mounted space between seats, so you can't lie over several seats. Hence for young children it's often easier in WT rather than WTP. Depends a bit on how well loaded the cabin is, since a full WT cabin will be uncomfortable - WTP being a much smaller cabin tends to be a more restful place from that perspective. As a very broad generalisation, WTP and CW are often the more busy cabins on longhaul at the moment.