Who is taking care of the kids when the 'door is closed'? I guess it depends on how old your kids are... I have a 4 year old and a 1 year old, so someone has to be watching them all the time.
Also, my house only has 3 bedrooms, and the kids take two of them. My office is in the corner of the living room with no walls. I can't lock anyone out of it.
Your house has to be large enough to support a home office to work from home full time.
Although if I wasn't living in this city I could probably afford a bigger house... we pay a premium to live within 10 minutes of work, so we don't have to face that 'two hour commute' you speak of.