All I can say from my extensive search for the perfect G75 bag is: Everki Titan
The bag is massive, the materials it's made from are all premium and if you travel a lot like me, it zips in half for TSA security checks. It took me a long time to get to this bag too.... I bought a Targus messenger - too tight of a fit, then I got a nice Samsonite bag hoping that would do, but there just wasn't enough room left over with the laptop in the bag. So, I searched for a while and was able the find the Titan which is usually $199.99 for $165.00 at Amazon with shipping (Walmart also had great prices) and I've never looked back. Here is a link to a Gadget review of the bag-
http://http://www.gadgetreview.com/2012/06/everki-titan-backpack-review.html It's a lot of cash for a backpack, but when you consider the value of what you carry in it...
Good Luck with your search, Hope this helps-
ASUS G75VW-RS72
CPU: i7-3610QM 2.30/3.30 GHz.
Memory: 16 GB PC1666 DDR3
Storage: Crucial M4 256GB SSD + Seagate Momentus XT 7200RPM 750GB SSHD
Graphics: GeForce GTX 670M 3GB
Screen: 17.3' Full HD LED Screen
OS: Windows 7 HP (x64) + Bitdefender Internet Security 2013
ASUS G75VW-RS72
CPU: i7-3610QM 2.30/3.30 GHz.
Memory: 16 GB PC1666 DDR3
Storage: Crucial M4 256GB SSD + Seagate Momentus XT 7200RPM 750GB SSHD
Graphics: GeForce GTX 670M 3GB
Screen: 17.3' Full HD LED Screen
OS: Windows 7 HP (x64) + Bitdefender Internet Security 2013