My personal plan on the way over is to force myself to stay awake, then pass out once we disembark at NRT and find our hotel. Figure that's the best way to bet jet lag and be able to hit the touristy ground running the next day.
On the way back, I suppose sleep would be nice, as we'll have a total of 24 hours in transit (and only 4 of that I think is waiting for a connection @ NRT) because we depart from BKK and head straight on back. I planned to have a few ambien handy.
I'm definitely not the world's most relaxed flyer, so whether the back facing would add to anxiety vs. front I have no idea. I am bringing a pretty big pillow for the trip =)