I have traveled all over Europe 4 times before and every time I wished that I had a travel pack that I could throw on my back when I went up stairs and then could also wheel around in airports and other flat surfaces...well I finally found the perfect travel pack at REI, just in time for my big trip.  It fits carry on, has a detachable day pack, plenty of pockets and straps and best of all...super durable wheels that glide smoothly, even over bumpy surfaces.  This perfect travel pack is called the Osprey Meridian 22".  You can also get the bigger 28" one, but it doesn't fit carry on. When I was at REI, Brad, the helpful associate, put 35lbs of weights in the pack so that I could make sure it fit right.  Funny thing is, when I got to the airport, I put my full pack on the weigh machine and it was exactly 35lbs!