I've only been in domestic J a handful of times, and it's been pretty different for me every time, so I can't comment much. I must say the most memorable was the snack on a short-haul that contained a piece of cantaloupe wrapped in meat.

According to what I've read around here, if you're on anything but the 762, it should be a nice experience. As for my personal comment on food, I don't like it much, but at least you get food. I've travelled in CX J before which has raised my expectations for J food. Having said that, I find the service to have been excellent everytime on AC though.

As I've also read around here, I think just dressing comfortably would be good enough. I've never looked around trying to judge what people wear.