I think ideally a home office should have its own separate entrance. I could come back from dropping Nugget off at school and go in the separate entrance, and imagine that the rest of the house does not exist. No opportunities for a "quick break" to throw in a load of laundry, empty the dishwasher, bake a loaf of bread and a dozen muffins, refinish the dining table ... Also no bed upstairs to lay down for "just a catnap."
Of course, just about every office has the mother of all distractions built in. I'll just take a "quick break" to check my email, read my blogs, scan the headlines, browse the sales, indulge my hypochondria ... this is why Jonathan Franzen is brilliant, whatever you may think of his novels:
Franzen works in a rented office that he has stripped of all distractions. He uses a heavy, obsolete Dell laptop from which he has scoured any trace of hearts and solitaire, down to the level of the operating system. Because Franzen believes you can't write serious fiction on a computer that's connected to the Internet, he not only removed the Dell's wireless card but also permanently blocked its Ethernet port. "What you have to do," he explains, "is you plug in an Ethernet cable with superglue, and then you saw off the little head of it." (Time, Aug. 12, 2010)