In reply to Rob Exile Ward:
Very difficult one, since Xmas is generally very crowded, very expensive, and dodgy re snow.
Crowds: Horrendous in France during school holidays.
Snow: very unreliable in the low resorts, such as Porte de Soleil and much of Austria - need to really watch the snow reports before committing anywhere there
Non-skiers: virtually eliminates the concrete, remote purpuse-built resorts such a Avoriaz
Expense: great everywhere, especially Switzerland. But worth weighing up the pros and cons carefully, because (as others have said) Zermatt, Wengen, etc are right up there in terms of real charm, great lift/transport systems and ability to get high quickly - and much the nicest for non-skiers