I'm sure an SD will wage in here, but in the meantime...

There have been a few posts on this previously I think. I've had my choice taken first on award tickets (and then sometimes not) - not sure this has anything to do with fare class, but rather the practice of the crew.

Sometimes, where there are last minute upgrades (at the gate), you get the ML*1 / ML*2 denotation on your BP, and this will be an indication to the flight crew that you aren't to get priority on meals. Otherwise, I think you're supposed to.