I had been looking at bags like this and considered making some out of cordura, tyvek, or canvas. The day after Bridit and I talked about making some, I saw them on Steep And Cheap for about $30 and got two. They swallow gear. Two take up 75% of the width of the Vibe leaving about 10″ on and they come up to the top of the seat backs.

The bags are of heavy cordura and lined with yellow ripstop. The lining has pockets around the outside which make nice places for tucking small things and the light color also makes it easier to find things in the cavernous bag. The bottom is hard rubber which adds weight, but it makes a bombproof bottom that can be set down outside without worrying about getting the contents or bag wet/dirty. I would like stiffer sides; it would make packing easier but storage more difficult. Three of the top edges unzip to form a lid that is a large pocket. The the rubber coated semi-transparent lid makes the pocket on contents easy to see.

There are handles on all four sides so grabbing the bag is easy no matter which way you attack it. The main straps work OK as backpack straps for longer carries.

We took them on a ski trip to the UP and had no shortage of space. Winter sports require so much stuff, but it all fit. One held ski gear; fleece, shells, gloves, socks, long underwear, wax, boot driers, helmets, and goggles all disappeared into the bag. One the way home I added a pillow and blanket. The bag still wasn't full. The other held clothes for three of us with plenty of space to spare. If I was traveling solo on a ski trip, one bag could carry all my stuff including ski boots and helmet.

Pros: Tons of space, Nice lining, durable, rubber bottom

Cons: Soft sides make loading and unloading a pain.