Andy_Panthro: If you could get Valve games without Steam, would you avoid Steam completely?
Well, there are ways that you can get Valve games without Steam, but not legally, and if you do get dodgy copies then you risk not being able to get on some servers. I don't know how easy this is to do, either, cause I've never tried.
Steam has some positives, like keeping the games up to date and giving one interface with which to buy games, play games, chat to players, find online servers, etc.
However, if I could get Valve games (like the Half Life series, Portal, Left 4 Dead, Counter-Strike, etc) then I would probably prefer it so that I have my own copy kept for myself that doesn't need the Steam client to work or be activated. Even so, even if I could get the games installed without Steam I'd probably link them to Steam for the client interface.
Basically, I just don't like how my games are utterly dependent on the Steam service existing, so to limit this I've only used Steam for Valve games.