Mystic Cat and I seem to have the same reusable bag routine (although when I'm running in for a few things, I just use the bag as my basket), so I don't have much more to add. However, I wanted to post a picture of the bags that I our local grocery store has...pardon the bass in the corner, the bags are mesh and very sturdy so one of the local fishing clubs uses them for their weigh-in bags and that was the only place I could find a picture.
Anyway I really like them, and I have 2 bags and that's usually enough for me, however I'm usually only shopping for myself.
They're selling these kind now too, but they're not as big and they look more prone to absorbing moisture to me, I haven't bothered with these ones.
If you do end up having to buy paper or plastic bags, instead of reusing them for trashcan liners you could always just bring them back to the store for your next grocery trip and reuse them that way.