not keen on doing really large areas, as , as pointed out a square ft/metre works out silly money, but I also don't like waiting to get paid either, and as many large areas are commercial, then I always have to wait 2 to 3 months to get paid, so really I like to do domestics at a higher sq ft price, do less work, and get paid on the day.
having said that, if I do get a commercial its always at the price I want, rather than the price they want to pay.