Hi, I'm not from Yorkshire, so I was wondering if someone can tell me which is the best airport to fly into - the most convenient to get to and the largest? Thanks for your help

The biggest international airport nearby is Manchester - about 1 and half hours' drive from Sheffield.
Closer ones are Nottingham (East Midlands), Leeds Bradford, and the new one Doncaster-Sheffield (Robin Hood) but I don't think these have as many flight operators using them as Manchester. Each one should have their own website if you search for them in Google.
Hope this helps

manchester = eek
i hate the damn place
try birmingham, not that far away for scheduled flights
or east midlands/doncaster for charters
manchester is pretty hard to get to

Hard to get to? There's direct trains between Sheffield and Manchester Airport.

Although if you're driving or hiring a car at the airport I'd say East Midlands is the easiest option - straight up the M1 to get to Sheffield.