There is a Karting track, up near Old Trafford, brilliant fun!! I was terrified going in as I don't drive but it was great. We hired the track so it was just us and no idiots with no consideration for nervous beginner karters like me :)
There is an indoor snow sports centre (Chill Factor E) which does skiing, snowboarding and other snow stuff and there's a climbing wall there. Good fun though if not a confident skier I'd recommend some taster lessons first - mainly group bookings, I booked one for my ex as he had never skied before.
If all else fails you can always call me to hide with an emergency glass of wine haha, I'm in South Manchester :) The ghost tours are a good laugh, I went on one years back with a guy, can't think of his name but he was hilarious, a bit tongue in cheek, he was all dressed up and everything! Lots of walking though.
One thing which is an idea to check is what is on the day you are out as certain places get very busy, when there are big name concerts on and football too with both City and United Games. Some nice bars like outside The Wellington/Oyster Bar get packed out as there is outside seating (and sometimes riot police!). Nice food in the Wellington, it's an old fashioned black and white pub they literally rebuilt bit by bit after the IRA bomb.