Kenwood hotel near (ish) town is nice and has some decent facitilities. Beauchief hotel is ok if you fancy playing golf. Aston Hall hotel is really luxurious but no idea about leisure facilities.
What you coming to Sheffield for? You fancy a pint or are you entertaining a lady?
I always used to stay here when working in Sheffield about 8 years ago. It was a Marriott back then. It's a couple of miles out of town.