I'm in the same boat as you. I have a decent bushnell 24-36x60 that was given to me, but I'm looking for a little more power and maybe a little better quality. I'll be paying close attention to the responses you get on this thread. I was thinking about going with this one Burris 25-75x70 XTS2575 Spotter
I love how compact it is, yet very powerful. I haven't looked through one in person. I'd say for $500 you'll end up in very good shape. Few guys at the other long range forum I frequent, love Kowa spotting scopes.