I lived in Manchester, I can go on and on but ofcouse there are some interesting places depending what sort of person you are. According to Sean that's about it if you are a party animal who just can't sit still and minute by minute you need to do get out and about. As for football fans there's two very famous football club.Man United and Man City.
Away from Manchester not that far ..there's Lake district,Peak district and non other than the famous Blackpool. Day trip will do the business.
You could prefer check it out on the net which is very helpful too as I may missed out interesting place.