How can I control iTunes from another Mac?
I've been using TuneConnect to do pretty much what you're after. It's got, what I consider to be, a much nicer UI that iTunes Remote Control. You install a server component on your iTunes machine and the remote component on the machine you want to control iTunes from and it just...works.

I've been running it without any issues on Lion. It ran well for me on Snow Leopard as well.