I doubt Bush would have appeared with Goss if he was leaving over some kind of hooker problem.
Here's a thought from another analyst:
It may have become clear to Goss that the W.H. will not allow the DOJ to pursue subpoenas or indictments in the WaPo/Mary McCarthy matter. If so, Goss may have reached the (reasonable) conclusion that he cannot succeed in rooting out leakers in the CIA if there's not going to be a serious effort at prosecution.
I think you're right. Goss would have quietly resigned - or maybe not so quietly, but without the presence of Bush.
I think this is something bigger than hookers. Even if they're big mommas...