Excellent post by Virginia Centrist about the correlation between party identification and lot size. I'm not sure large lots necessarily put the GOP at a disadvantage in terms of canvassing - witness the growth of gated communities in Northern Virginia and Richmond. The GOP does have difficulty putting on a good ground game in rural areas where it can take an hour to knock on 5 doors. But gated townhome communities and condo complexes that bar any type of soliciting in urban and exurban areas hamper Dem efforts as well.
Like Virginia Centrist, I would love to see one of our political patron saints - The Real Sabato or The Real Rozell (or even The Real Holsworth) - tackle this one.