Personally, however, I'd prefer the reverse: offices as the default (two people per office okay, as long as there's space) with open space (with portable white boards, bean bag chairs, desks) in the middle for ad-hoc design/discussions.
Cubicles do seem the worst of both world, however: an ad-hoc meeting is no longer so ad-hoc (as it requires hunting for an available conference room), but the noise/interruption issues are no better than open areas.