I loved The Bridge! The first three Culture novels are exceptional: Consider Phlebas, The Player of Games and Use of Weapons. Highly recommend all three. The rest are probably great too but I haven't read them yet.
I also recommend The Crow Road.
Although if we're talking AI, Excession.
I tend to start people on either Use of Weapons or Player of Games depending on the person. Excession is IMO a lot easier to appreciate when you've already got your head around the Culture, Minds etc.
Me too. Especially "Player of Games." I re-read Weapons just before Algebraist...it's long and very introspective, whereas Player is easier to just follow along with the plot. If people don't like Player, they're not going to like Weapons, but I'm not sure the reverse is true.
I think virtualizing consciousnesses is most thoroughly investigated in Surface Detail.