I have two similar to the envirosax that I have had for years. They can be laundered, weigh nothing and hold an impressive lot of stuff.

I use the nylon bags that fold into tiny packets. I toss them into my regular handbag and then can take one out and unfold it when I need a shopping bag, and they work for clothing or for groceries. I don't prefer to carry a large shopper bag as a purse, so it is easier for me to carry a regular handbag with the nylon totes stowed away inside until I need them. I don't remember what brand mine are, but they came in sets of 4 or 5.

Gaylene makes some good points. I have a Baggu bag that I don't use as often as the Envirosax because a) you have to stuff the empty bag in a separate little pouch that is not attached, so it's easy to lose, b) the handles are shorter so they don't fit over my shoulder easily, and c) the fabric is stiffer and somehow more slippery so it slides off my shoulder even if I try to carry it that way. When one of my Envirosax starts to show too much wear (I've had them 3-4 years and still going strong), I'll probably get another one of those instead of a Baggu.

Oh, ha, I should mention that i rarely ever actually pack my Baggus and Envirosax back into their pouches. Most of the time I just wad them up and stuff them in my purse.

I was using a baggu *as* a purse! I upgraded to baggu's little leather cross-body purse for actual purse use, which is an improvement, but I still use the nylon baggus all the time.

So based on all these helpful hints, I think I may need to do some trial runs before I commit to a bag. I do have loads of ugly logo-infested versions of all these various shapes and sizes at home already. What I should do is just try the various shapes/sizes and see what works for me. Then I can go out and purchase an attractive (logo-free and neutral colored) one in the style that works for me after I have done my research.

When I was at the mall yesterday, I specifically scouted out the other shoppers to see what they were using and everyone just had their arms loaded down with paper store-provided bags...exactly opposite of what I am trying to accomplish!

I'm late to the thread, but thought I'd let you know about the Tom Bihn shop bag.
It's ultra-durable, but not super packable. I've used mine for countless excursions. It's easy to clean. It was so expensive (to me), that I've not lost it in the past 4 years that I've had it

It's made in Seattle to boot!

http://www.tombihn.com/PROD/TB0608.html

ETA: Oh, there's a logo on it, but it's kinda small.

Smittie - those Tom Bihn bags area amazing!

Another vote for the EnviroSac. I travel a lot. I always have one or two in my carry on. It comes very handy if u purchase something from duty free or for carrying jackets or to keep your valuables just in case the airlines want to check in the carry on.

I like the bags that fit into a tiny self-contained sack too. Very easy to toss into my purse. I always forget to being the big reusable bags with me into stores, and Seattle now charges you a small fee if you don't have a reusable bag.

I use a black-and-white polka dot bag from ChicoBag -- similar to those on this page. It can be stuffed into an attached small pouch when not being used, and then just tossed into my purse.

I have an assortment of very basic canvas tote bags which are patterned, but not with a logo. One is leopard spots, one is red with white polka dots, one has an American flag print, etc. If I'm going out shopping and I remember to grab one they are very handy.

I also have a faux Longchamp Le Pliage style bag that I often carry if I'm going out shopping. I'll just take the bare minimum of "purse" items (e.g. sunglasses, lip balm, wallet) so that my bag is mostly empty.

I'm starting to feel like there are TWO different shopping bags I need to have. First is the little nylon one that I can keep in my handbag for random shopping that happens when I just out doing my errands. The second is when I make a big shopping trip that is PLANNED....Like right now, I have 2 items that I want to return. So they are sitting in my returns zone until I make a PLAN to go to the mall to reverse-shop. I would like a flat bottom style....the bags that can stand up by themselves...for this purpose since I can neatly fold the items and place them in the bottom of the bag in layers with their receipts. This style doesn't need to be small to fit in my handbag and I could easily slip my wallet and such into a side pocket and even leave the handbag at home! I wonder if this plan would resolve my challenge....