Wouldnt a cat, or a rabbit or something be more suitable if you intend on leaving it alone for so long, so often?
8 hours a day, 5 days a week alone? As a puppy? That dog, no matter what breed it is, is gonna present problems.
After all, you arent it's 'master', just some dude who shows up at what it will see as his/her house every so often. Sure, it'll be glad to see you and all, just dont expect much obedience from it.
What you are talking about is increasing the size of your family by one, not just 'buying a dog'......dogs take a whole lotta time and love, just like kids.
Treat a dog just the way you would your own children, and you will end up with an obediant, loyal, loving, great fun pet and best mate, who would lay down his or her life to protect you or your family or property without a second thought.
Treat it like a dog, ie, chained or locked up for long periods of time, and you will end up with a canine, of dubious loyalty, and most probably rather annoying habits (like eating your mobile phone/ TV remote, digging out the wife's favourite rose bush, tearing your laundry apart etc.)
Anyway, just thought I'd throw my 2c in....be fair to the animal, would you like to have been left alone all day chained up while you were growing up? What do you reckon you would think about the person who did that to you? Do you think a dg is all that much differant?