I've signed up for the Peterborough half marathon again this year.
It's in February... last year it was around freezing and clear, quite pleasant, but it could just as easily be -20c, you never know until the week of the race. Flat and fast, I don't think there's a hill on the entire run. Not very scenic, but well organized and works out where with where my fitness will be in Feb.
2007 time: 2:07
2008 target: sub-1:55
2007 was my first half marathon and my first year of running... so it wasn't too terrible, but I ran out of gas at about 3/4 distance... I really didn't prepare enough.
2008 will be different! I'm mentally prepared to do it right, and physically I'm in much better running shape.