Lived in Plymouth all my life until 2010 and for years been sledging up there, as advised by Beast etc, apart from the roads being dodgy and blocked with cars, Princetown area will be full of people, but if you go on the northern side towards Postbridge or even just outside Princetown, near Two Bridges it should be less manic!!
As someone has suggested; The Road (A386)south bound from the A30 towards Tavistock has many good places with higher Tors - that are accessible - Sourton being one, but a number of spots are along that route. Jealous - HAVE FUN, looks like there will be a good snow covering up there!!