You know, with everyone in such a state about shopping bags, almost nothing seems like a good option. Ordinary plastic shopping bags take forever to break down, get eaten by wildlife etc. Biodegradable plastics are expensive or don't work. Reusable green bags wear out and are made of pretty much the same stuff as the original plastic ones. Maybe the best option is to use unbleached paper bags made from recycled paper pulp. They go straight back to our home recycling bins to be remade into new bags. No fuss, no mess. The only problem with them would be strength, and I'm sure we can get around that one if we try.
Mokalus of Borg
PS - Or we could all get those old-style trolley bags.
PPS - But I'd feel silly with one of those.