-Actually enforcing the "forward lav is reserved for F passengers" rule. It's not so much that I mind other PAX in the lav; god knows how many people have been in the lav that day, a few more won't hurt. It's the parade of people up and down the aisle that I find distracting and annoying. The aisle in F is not supposed to be a high-traffic area.
-Doing it all the same way. If you're going to place a bottle of water, pillow and blanket on the seat before boarding, do it that way on all the flights.
-A little more variety on the beer selection would be nice. Even if they keep only 4 beers at any one time, it'd be nice to see something other than bud/bud light/the other 2 I forget.
-The FA's should always call us by name.
Of course there's a ton of other suggestions (like don't take any more seats out!!!) but these are just cheap/free ones...