DH and I travel a lot - not just the trips in my siggy, but before we were married we'd both been to Europe a couple of times and he literally took a trip around the world one year. I had hard-sided luggage for my first European adventure. Never again! That thing was so heavy when it was empty, I could barely get it moving when it was full (and it had wheels). It was good quality, Delsey, but still got chewed up and was covered in scratches, dents, and dings. I won't get hard sided again. I bought cheap Target soft side years ago and they fell apart after a few trips. We have mid-grade soft side now and they're good. We've flown with them a few times and taken them on cruises.
For DH's around the world trip, all of our overseas flights, and a few domestic flights in the last few years we took high quality Osprey backpacks - that is the way to go!! You have your hands free and don't have to worry about carrying or pulling a bag around cobblestone or uneven streets. A lot of people think a backpack is too heavy/hard to deal with. I have scoliosis, a bad hip, a bad back, and I'm a small person - if I can handle a backpack anyone can! They are sturdy and lightweight. They hold a TON! No problems with breakables - just wrap your things well inside. Love, love, love my Osprey Waypoint backpack!!