I agree Alistair that Domaine Carneros is excellent, but the local Mumm Napa product many experts rate higher than the French Mumm and Domaine Chandon is also highly rated.
English Nyetimber has done extremely well
in a blind tasting in Paris, has this got shades of the Judgement of Paris in 1976? Certainly as I advised previously, Taittinger is not the only champagne house to have bought land in the south-east of England so we can expect more such initiatives in the future.