You may need some noise-cancelling headphones in case your wife wants you to switch seats so she can chat to her sister

- Fully agree on the hand towel (remember a ziplock bag to store the wet towel), the hot towel is one of my favorite perks of J. Bringing your own towel is the next best thing.
- PJ's are a great accessory for Y, as you are cramped, change after dinner, nap/drink/sleep/etc...and before landing change back. It always feels better to put on a clean'ish set of cloths after a very long flight, especially when you have a warm towel for face and arms.
- An ambien/benadryl/other med to make you sleep can do wonders in long J flights.
- Airline blankets make great picnic blankets when traveling, so it can be a worthwhile investment on the plane (buy early in case they run out), the pillows generally suck, I find a fleece jacket or sweater works better.