I have two Old English Bulldogs that I leave out all day. They'll regularly be left for 6-8 hours and sometimes over 12. They have almost full run of the house and I installed a dog door in our sliding glass door so they can go outside as they please.

I don't feel bad and they don't seem to mind. I'd feel bad if I crated them but as a part of my home security system crating them would be counter productive.