Duffel bag to check in?

It is not clear if you are aware that if you buy wine before going to the airport you will not be able to carry it on. You will have to put the wine in your checked luggage. Otherwise the wine that you can carry on is at the Duty Free shops after you go through security.

edit: Last summer I successfully bought five 12 ounce bottles of beer from Belgium in my checked luggage by wrapping them in bubble wrap, paper, and then my dirty clothes.

As was just mentioned, no wine in your carry on unless purchased at duty free after security. If you really, really want to bring back wine, you'll want to do the opposite of your plan, which is pack the wine in your hard shell carry on and check that. Be sure to pack bubble wrap or bring these doodads made just for that purpose. In my opinion, drink the wine in Italy (it's better in person, anyway) and bring home other gifts that aren't so likely to ruin your suitcase.

This thread covers the question you asked and provides plenty of suggestions for packable bags: https://community.ricksteves.com/travel-forum/packing/packable-bag

You will not be able to carry on wine or any liquids over 3 oz, unless you purchase them at the airport. If you want to purchase wine you have a couple of choices. One would be to have it shipped home. I bought a case of wine and the cost was 100 euro to ship home. The other is to pack them in your checked bag. I have brought back liquids in checked bag and they made it just fine. Place the bottle in a zip bag, if you have one. Then roll dirty clothes around bottle to help pad it. Next, place bottle between two layers of clothing. Using this method I have not lost a bottle, yet. Also, you might want to purchase some bubble wrap or even bottle packing slips.

Here is a link to tsa.gov/travel/security-screening/whatcanibring

Yes everyone is right about the wine, I have experienced it before. Good luck!

erectoch3, yes, this is what we do. Except I usually take a squished up empty duffle on the way there in my carryon, and check it on the return full of dirty clothes (things that can be replaced). That makes our carryons lighter for souvenirs, and more valuable things. We will also put carefully packed wine, olive oil, jam, honey, etc., in the duffle, and so far they've survived. Certainly you can find cheap or not cheap duffle bags over there too, brands you'll recognize. Just go to a shop, not a street vendor.

I've used a number of different brands, REI, Lands End, Jansport, old gym bag, and a very lightweight North Face. It doesnt need to be expensive. Some fold up into a hand-sized packet. You might want something sturdier if its going to be heavy with food.

We use WineSkins to pack bottles, with carefully arranged pieces of cardboard, surrounded by clothes to cushion them. We use socks on other things like jars of jam. Just pack it so the things don't jostle around and hit each other. The danger to bottles is really from hitting a sharp edge (like a table edge) so it takes some thought on packing them. But it does work.

I was thinking about that....DOH! Yes..I am aware that wine cannot go on carry-on...brain fart.

Also, unless your first destination in the U.S. is your home airport, the bottles from the Duty-Free shop cannot be carried onto a connecting plane -- they would have to be checked.
We carry a soft bag so we can check in fragile / heavy purchases (like glass jars of German-made Nivea cream, bought at our final stop) safely inside hard-sided suitcases taking the place of bulky clothing which goes in the carry-on soft bag. Have used a "don't tell Rick" bag, but you can buy inexpensive bags in Italy so you don't need to carry an extra bag for your entire trip.

I think it would be better to check the hard shell carry on (with wine) and use the duffle for carry on. Walmart has a number of lightweight duffle bags, but the bigger they get, the heavier they get, so keep weight in might. Your AAA, RS store, or REI should have packable duffles for consideration. I stick to the Walmart ones and I don't fold them, but lay them on the base of my suitcase, or in the outside pocket of my soft side suitcase.

May I suggest -- tuck a few extra large ziplock bags into your suitcase before you leave so you can put into them any liquids you purchase and bring home in your checked luggage. If red wine bottle is broken in transit, perhaps your other items will be spared the stains.

I think it would be better to check the hard shell carry on (with wine) and use the duffle for carry on.

Agreed. We carry a folding square bag (about the size of a small work out bag, but it folds flat) with us on our trips. That way if we find we picked up one too many souvenirs or want to check a bag for wine, olive oil, etc., then we have options.

I'd look for a bag that folds flat. This one by Eddie Bauer

http://www.eddiebauer.com/product/stowaway-40l-packable-duffel/82302379?showProducts=111&color=062&sizetype=Regular&size=ONESZE&color=062&cm_mmc=GooglePLA-_-non_brand_PLA_Gear-_-82302379-_-0232379062000000&cvosrc=cse.google.0232379062000000&cvo_campaign=non_brand_PLA_Gear

is too heavy, probably, but that's the type of bag I'm describing.

It's not exactly "foldable" but if you're interested in a top quality, U.S. made Duffel that will last a lifetime, have a look at this model - https://www.redoxx.com/safari-beanos-bag-pr4/91030/product . I've been using one for carry-on for the last few trips, and it works well.

You could also have a look at the Tom Bihn products as one of their bags might work well for you.