My mission for the perfect traveling bag started 4 years ago. Yes, it was a long one but I was not about to buy 4 bags, compare them all, then go to the post office with the returns.
  Please bear with me. The back story is important here.
  It began with a medium sized 4wheeled bag for my wife and a medium 2-wheeler Burton for myself.  She liked the ease in pushing her stand-up luggage over the airport's smooth floor but once out in the real-world her bag was more easily pulled using just 2 of its wheels. Which was actually 90% of the time. During its 4th voyage, while traveling over pebbles to a oceanside hotel one of its cheap plastic wheels started to malfunction. It never rolled smoothly after that day but we did use it for the return trip home. Well, it was still under warranty but they would only repair it if I sent it back to them. That would be $10 for a cardboard box from staples and probably another $30-$40 to mail it back- To repair a $80 used bag?
  In the mean-time, my Burton luggage rolled-on like a tank due to its skateboard type wheels which always survived the baggage handlers, but alas- on its 5th trip, one of its zippers simply disappeared. Discovered this at baggage claim where I made a damage claim. The airline offered me a new bag of equal size which I promptly rejected because It wasn't even close in quality to mine. The problem was taken care of using a zipper repair kit ordered here on amazon.
  Both of these bags juuuust make the size limit for carry-ons. Which, for me is more often bad, rather than good. Reason being... It was a huge hassle trying to find room in the overhead compartments of economy class (I prefer to spend the money on trips to exotic locals).
  So, we decided to leave our wheeled luggage at home and travel with backpack luggage made for active people. I started looking for pack that had a rectangular shape with a flat bottom and deep sides for maximum capacity, and it should have compression straps to cinch it all in to fit in those overheads.
  When I first saw the eBag MotherLode I knew it was large enough to handle a week's vacation worth of clothes. You see, over the years I've learned that less is more and I believe most frequent fliers come to this realization eventually. Instead of bringing alot of clothes, just utilize a washing machine or the hotel's laundry service.
This bag can easily hold my 10 day load;
1 pair casual cotton pants
1 pair blue jeans
1 dress slacks
belt
2 casual long sleeve
1 dress shirt
2 t-shirts
1 nice pair of black shoes
2 wool socks
2 wool briefs
(lightweight wool underwear is simply amazing for travel. You can clean it in the sink at night and it will be dry by morning. It's itch-free and anti-odor as well. I've found the best to be made by Icebreaker.)
Sounds like too little? Not really because i fly wearing loose-fitting casual pants, long sleeve shirt, t-shirt underneath, socks and casual shoes.

  Back to the bag. It looks like a backpack but packs like luggage. The zipper goes around 3 sides so you can pack comfortably. There is a fabric divider which will keep things from clumping at the bottom of the bag when it kept in a vertical position. I put my shoes in plastic bags and packed them in the "south" of the bag with my pants and heavier items while my shirts go in the higher level with the light stuff. Of course, the zippers can be locked.
  Besides the large main compartment, there is a zipper which opens to add another 2 inches of capacity. I've never had to use it and i imagine that if I did, this bag would become just as large and unwieldy as wheeled luggage. But it's good to know that if i need the extra space to bring back any "great finds", I can load it up and check it in.
  Next up, the laptop compartment which I do not use because smartphones are just as helpful in a wifi equipped room. And I do make sure my hotel had wifi before I book it. So I use this easy to access area to hold a book or two. This pocket can also be locked.
  Then there is a small dual zippered area on the top front. Looks like it's been made seperate to hold used socks/underwear or light shoes. I do not use this pocket at all because it opens way to easily, so I keep a small tsa lock on it at all times.
  We now move on to the second largest compartment. Here you can keep everyhting else that you will need like cameras, chargers, electric shavers, books, etc... Very good size for a secondary area. Along the inside of the flap there is a cell phone pocket, and small mesh pocket, and two zippered pockets for documents and wallet. Can also be locked.
  The next zipper is vertical and secures a pocket along the outside of the pack. Here is another good place to keep a book. Specifically the one you will need easy access to.  This area is not lockable.
 There is another small zippered pocket off to the side in which is stored a bottle holder cinch sack which you would use while actually carrying the pack on your back as it sticks out too far to keep a bottle in here while doing anything else. Not lockable.
 This brings us to the final compartment on the back of the pack in which hides the carrying straps which can be attached very quickly and easily and are very well padded and make carrying this pack around very pleasant, even for long distances. If you feel the desire to run you simply attach the chest strap (included, along with waist strap and a shoulder strap)  which enables the pack to stay the course.  It's zipper can be locked as well.
  Oh, and there is a carrying handle on top and one along the side and a "pick up strap" along the bottom end so that you don't have to touch the bottom of the bag when lifting in that manner.
  I do believe I've covered it all.
  Mission accomplished.