I use a Foray made briefcase (it has a detachable shoulder strap) that is designed for 17" laptops. The G55vw fits snugly top-to-bottom, and there is just enough clearance on the sides to put the monster of an AC adapter (I have to put the power cord into another compartment).
All-in-all, I'd say that I like this case, and I'll be looking for another like it (although this particular style has been discontinued, and to my great discontent) in a few years when I end up replacing this laptop.
The link below is to a Targus bag I used to use, and the laptop fit nicely.
http://www.targus.com/US/16-revolution-checkpointfriendly-topload-case-ttl416us