I travel 30 weeks per year (at least) and I always fold. Never even owned a garment bag.
I use this method, and I make sure not to pack my carry one or suitcase extremely tight. It can be full, but not "sitting on the suitcase to close it" full
The method: http://lifehacker.com/5723295/fold-a-suit-coat-for-packing-the-right-way