I'm in London, UK and I just bought a set of Marathon Winter tyres, 35mm. Decent tyres, held up well during the snow! Am running them all winter just incase any ice shows up - not much penalty for doing this, also when you change tyres you are much faster!

Otherwise I run armadillo tyres the rest of the year - excellent tyres, almost bombproof and decent grip. Only thing I'd say is heavy and harsh ride, but if you don't want to fix punctures...

I think I may switch to "normal" tyres when these armadillos are worn out just to see what they are like, but if I end up getting loads of punctures then I'm going back!