I’m going to be in Manchester next Monday for the day. Any recommendations for things to do in/around the city centre?
Jaysus, is it that bad?
What kind of things are you interested in? Touristy? Culture? Off-beat?
All sorts really. Touristy stuff is fun once it’s decent. Cultural stuff, off-beat is always fun. I’ve been in Manchester twice before but once never made it out of Chorlton and the other time was spent admiring the décor in Irish themed bars. 
There’s the Museum of Science and Industry, Lowry Centre, John Rylands Library, Manchester Art Gallery, Old Trafford, Urbis, etc.
The City Art Gallery (edit: what Capt. Ridley’s Shooting Party called it), on Mosley Street between Piccadilly Gardens and St Peters Square is certainly worth a look. The Museum of Science and Industry is a good one, too. On Deansgate, there’s a new visitor centre for the John Rylands Library (part of the university), which is a Victorian Gothic architectural curiosity worth seeing - kind of a cathedral-in-miniature. I’m not up to speed on anything to suggest food-wise, however, beyond the obvious options such as Chinatown or the Curry Mile. Oh the other hand, if you want to drink in a good pub rather than an overpriced wine bar, the Briton’s Protection, near the G-Mex tram stop, has great beer, and a really well-preserved old interior, with cosy little rooms hidden away down a corridor behind the bar.
Based upon my reading of the 5-day weather forecast for that fair city, I heartily recommend a visit to an umbrella shop before taking up any suggestions given upthread.
Are you allowed take umbrellas on planes these days?
I’ve beem to Urbis before but I see they have a videogame exhibition on at the minute. We might pop into that if I can drag the better half!
In the end I visited Urbis and the videogame nation exhibition. £3 in and well worth a gander if you’re interested in videogaming and are at a loose end in Manchester between now and September. I found the older parts of the exhibition with the microcomputer games etc. more interesting than the more modern parts. They seemed to just be tradeshow stalls for the most part.