I had lots of fun researching venues for our wedding but in the end went for outdoor hog roast and a party at the Harley Hotel rather than traditional sit down meal (not sure if they're brave enough to do it again).
However, I did stay at Kenwood Hall to get ready for my wedding and many of our guest stayed there and loved it. The junior suite was lovely but lacked facilities like a fridge, and robes (which were brought when asked for). I also attended a wedding there and the BBQ in the evening was lovely and the grounds are just perfect for photo's. They do often have up to 3 weddings on at same time though.
I got married at the Bandstand at Weston Park and details of my wedding can be found at http://www.hansleybeard.co.uk/weddings/sara_daves_wedding
Channing Hall (Victorian splendor with spiral staircase) on Surrey Street is great for a reception on a budget but you do need to provide own caterers and drinks and you need approval from the Trustees of the Upper Chapel unless getting married in said Chapel first.
I also know people who enjoyed their reception at the Ivory off West Street and I liked the look of Firth Hall at Sheffield University and also Cutlers Hall on Church Street both very grand indeed.
Happy planning!
PS: My wedding planner was ace Jennie Beard (website link above is hers)