The main thing you get for your extra money is the ability to sleep on a long flight. WTP isn't all that wonderful for sleep, you get a recliner and a footrest and the armrests are a bit obtrusive. I've slept better with some sort of neck support (I use a chinese knockoff of TRTL) in WT. The food in WTP isn't a major upgrade to WT, though CW isn't tremendous.

I'd do this quite happily WT out and CW back. On the way out you have the trip to look forward to and reasonable energy levels, on the return you'll be tired and will want sleep.