I remember a Sports Illustrated article years back that quoted an O-lineman from the NFL saying he didn't get really good until he developed a "Fun House Mirror Butt." Made me laugh because I finally had a good term for my backyard.
Get your upper body larger and you'll seem more proportionate...definitely not the Brad Pitt look, but then you've gotta decide what type of physique you want. I can't put on any decent muscle without include squats/deads/good mornings, etc. And with those comes the ass...at least for me.
High bar squats with heels elevated on blocks or plates takes some of the emphasis off glutes, but most guys can't push much weight that way.
The other question is, what's your body fat? A muscular ass is one thing, but a fat, dumpy one is another.
(I feel like I need a shower after discussing a guy's ass like this...not that there's anything wrong with it, right?)