I'm a fan of messenger bags myself... These ones were fairly simple to do...

But I bet that totes would work too... These were my very first sewn bags...

Or you could even add a gusset and or closure to the top(like a zipper, magnet, or snaps/buttons). Craftster.org has a bunch of great tutes
here. I'd be happy to help and answer questions if you'd like... Good luck!