Carry on Luggage - Travel Light & Smart
This is the single most important item to "get right". Your carry on luggage has got to hold everything you'll be taking, plus fit in the airplanes overhead storage compartments. For most airlines, the dimensions must total less than 45" (length + width + height). The best size is 21" long by 15" wide by 9" deep. A close second choice would be 22"x14"x9".
Soft-sided is preferable, but it needs to be constructed of a durable, rugged material, with plenty of pockets, and reliable zippers. One really handy feature to look for is expandability. This is usually accomplished with a zippered front, which when undone, adds one to 2 inches of thickness.
It should go without saying the bag must have wheels. They should be in-line skate wheels that utilize sealed bearings. Check to be sure they spin smoothly with no side to side play.
Make sure the handle is collapsible, and collapses inside the bag - not outside. On larger carry-on bags, avoid getting one with a T-handle as most of them aren't near as steady as they ought to be and provide less control of the bag. However, the T-handle is great on the smaller backpack style, or duffel.
If you will be carrying a second smaller bag, like for a laptop, briefcase, or small carry-all, then be sure your selection comes with an add-a-bag strap so you can hook the smaller bag to your roll-aboard.
Quite frankly, these bags don't have to cost a fortune. I've found great deals at both Wal-Mart and Target stores for around $85, when they had some special buys. But if you don't want to wait, or just prefer avoiding the hassle of shopping, check out selections at eBags. A couple smart choices are shown here, but once on their site, you'll find a world of selections.
Both of these bags cost around a hundred bucks and are jam-packed with the most desired features.
First is this Lite Altitude 21" Expandable Wheeled Upright Pullman/Carry-On by Kenneth Cole. With a rugged and durable exterior, tear-resistant lining, and garment restraints, there are also zippered exterior front pockets for added capacity.
Other features include ultra lightweight materials, in-line skate wheels, locking retractable handle, a removable wet pocket, & removable garment sleeve with anti-wrinkle bar. 
The second is this Router Wheeled Laptop Convertible It has side-load laptop storage with lots of padded protection providing easy access and total isolation from the rest of the bags contents.
An efficient organizer, plenty of pockets where you need them, a sturdy mono-pole handle system, cavernous main compartment, plus lots of other great features make the new Router Wheeled Laptop Convertible an excellent choice.