I was pleasantly suprised when I had both of mine, people came for short visits and then went home. I didnt tell anyone I was in labour, and when I wrote my text I said visiting best between x-y times.
It is def. good idea to make a sign for the door and hang a note pad and Pen up so people can leave you message and you can get back to them at your own convienience. Mine said "Mother and baby resting, Disturb at your own peril!! hehehe

Anyone that just rocks up though, and doesnt realise you need your rest, is a bit rude, so dont feel bad about telling them you are tired and it is time to leave.