As many as the client requests. I have one in each area, inspector and attorney I like the best but if the client wants more choices then they get them. Some people want to shop around and others just want to take our advice so it is up to the customer.
I normally give 3 references for any service they may ask about. No specific order unless they ask for a specific city, in which case I will give closest to furthest. If I have more than 3 that I respect equally I will give more, but probably no more than 5 or else it is kind of pointless.