Altough I agree with everything said here and derek lapp gave a clear and correct answer; for me personally I tend to design the main page together with another random section of the project I'm working on and then present that to the client.
Of course it may not be the very end result that I'm presenting either, but sometimes it can be.
Reason for this is because I feel any other way is just too vague and altough this way potentially creates more work for me, I like it.
I guess I trust my own judgement enough to go on a limb.