The problem with reusable bags is actually reusing them. At my apartment, there is reusable bag upon reusable bag (mostly the kind you can buy at the grocery store that resemble a paper bag) but for the majority of the time, they sit there unused. About a year ago, however, I received a Hidden Tote by Timbuk2 and finally found a fabric bag I would reliably carry aorund and toss my groceries in.
Timbuk2's line of hidden bags are made 90 percent of recycled PET (the plastic used to make bottles) and ten percent nylon and the benefits are that the fabric is lightweight (the heaviest one is 0.4 pounds) but can hold a heavy load and is rip stop so won't tear. In addition, even after you pull the bags out of their folded-away pouches, the fabric remains relatively wringle-proof (which is something missing that irked me about other bags I have tried in the past).
The Hidden Tote is my favorite because of its easy of use. It zips up into a petite package and then can be opened up and slung over one's shoulder to carry home dinner. It's a reusable bag but doesn't look like one.
My least favorite of Timbuk2's Hidden series is the Hidden Brown Bag. While it too zips into a small rectangle that easily fits in a medium-size purse, the handles are too short to carry the bag over one's shoulder and the bag is too long (for 5-foot-2-inch me at least) to carry without risking running the bottom of the bag against the pavement.
A surprise to my liking was the Hidden Backpack. Like the Tote and Brown Bag, the bag folds into itself and then zips open, with the sides of exterior of the folded-away pocket becoming the base of the bag, which offers sturider support on the bottom. What I liked about the backpack is that it buttons closed and holds goods--and a fair number of them--snuggly inside. I could best imagine throwing one of these inside my suitcase when packing for a trip or tossing in a water bottle and snacks if going out for a hike.
The newest to the Timbuk2 Hidden collection is the Hidden Messenger, launched this year. The genius of the bag is that instead of folding into a rectangle that becomes the base of the bag the way the others do, the Messenger folds into a pocket that then becomes an interior pocket in the messenger bag. It's nice because the bag only closes by buckels, meaning you have a safe place for keys and IDs in the zipper pocket. The Messenger isn't large--it measures in at 12.4 inches wide by 6.5 inches tall and 4.9 inches deep--but it'd also be great as a daypack when traveling or a purse when running quickly to the corner store.
For me, the best thing about the bags is that I actually use mine. Fortunately, the prices are also right: the Hidden Tote costs $22, the Hidden Brown Bag is $20, the Hidden Backpack is $28.00, and the Hidden Messenger rings in at $30.00. For more, visit timbuk2.com.