I like big bags and I cannot lie. Seriously, love 'em, but not when they weight a ton all by themselves and take up half your closet. Sea to Summit has awesome alien nylon technology that they use to make freakishly strong but light bags.
The Ultra Sil Travel Duffel is 2.8 ounces, stuffs into its own deck-of-cards-sized pocket, and is strong enough to pack its 40 liters of space with pretty much whatever you want. The siliconized ripstop nylon is water resistant but definitely not waterproof, and it's thin enough you want to beware of scraping and poking with sharp objects, but if you just want something that weighs and packs away to nothing yet still will carry a big, heavy load, the Ultra Sil Travel Duffel will do the trick.