I always have my small, wheeled suitcase. It is about international carryon size, smaller than US airlines carry on size. It is small enough to fit in front of me when sitting in panels and sessions, so not hanging in an aisle or taking up the space of people on either side of me. And I’ve not had any problems with it on the show floor.
I have found it makes things much easier - Water & snacks go inside, plus a light sweatshirt or wrap, and my small folding chair fits inside as well. Much easier on my shoulders & back than a backpack or carrying a lot of bags. Most purchases will also fit inside...unless the purchase is something really large.