The
Porter Case is an incredible invention. I have two of the earlier models (Elite, which I got first not realizing it was smaller, and the PCII, which I use anytime I travel now). (They're actually made here in South Bend. I actually found out about them by accident while looking for someplace local that could fix my old suitcase).
It's sized to be a legit carryon for any airline (a lot of carryon sized bags are too large for many airlines, especially now that several US lines have reduced the allowed size). It has large ball bearing wheels. And most importantly, it unfolds to become a handy cart that you can fit all your other luggage on.
It's made my travel so much easier, whether I've got my camera gear in it or not (mostly I remove the camera dividers and use it as a carryon bag and carry my camera gear in my saddleback gadget bag). I remember going through a 2.5 week long honeymoon (my last vacation before buying it) with wheeled bags tethered to each other like a dysfunctional train, and every few minutes one of them would flip or something and I'd have to stop and untangle it... it was just a huge pain in the butt. With this thing, I just flip the handle, pile the bags onto it, clip the strap to the base and thread it through the handle, and I'm good to go (only really need the strap if I'm carrying something small/lightweight on it, like my normal camera bag or laptop case).