I am somewhat of a luggage junkie and take a visit to the luggage stores to window shop any chance I get. My current roll-aboard (by Connections) has been quite a trooper and it's a very simple case.
Here are the features I always look for:
1)
Try the handle on the suitcase. Does it release easily? Many of the new Samsonite cases have buttons that must be pushed to release the handle -- I find these awkward. Also, make sure the handle is long enough so you aren't kicking the suitcase as you walk along. Does the handle click or lock into place when fully extended? Sometimes I like to lean lightly on it while I'm waiting and don't want it to fall back into the suitcase. The locking mechanism should be sturdy. How is the handle itself attached to the extending bars? Make sure it is firmly attached with screws -- sometimes those puppies can just fly off as you're running down the concourse!
2)
Examine the wheels. Obviously, this is the most important part of a
roll-aboard suitcase. I've always found that wheels literally built into the case itself (i.e. only a small portion is showing) are the best. Wheels that protrude too much or that are simply fixtures break off too easily with rough baggage handling. Plus, they take up more room in the overhead bins.
3)
Look for a "rounded" frame. That's my own term. Most of the suitcases these days are built with
a frame that goes around the width of the suitcase. I've always found that suitcases with
a frame around the length of the suitcase (a) look more streamlined, (b) are sturdier, and (c) fit into overhead compartments much easier.
4)
Make sure you get a good size. Size is important in these days of luggage sizers and surly FAs... especially internationally where the overhead bins are smaller and the FAs more scrutinizing. Not only how big the bag actually is but also how big it
looks. You want a bag that
looks small, but can hold a lot. You seem to have a good handle on the size you want. Attempt to find something that is ultimately no bigger than 22". Another feature I hate are the "expandable suitcases." This is luggage where you can undo another zipper and, voila, you have an extra inch or two to pack in. While a good idea in theory, this adds weight, bulk, and makes the bag look ugly, IMO. I can hear the Lufthansa FAs now: "That will not fit in our overhead bins. Give it to me now and I will check it in."
4)
Pay attention to those outside pockets.. This may be personal based on your travel habits. I always like to get a small outside compartment at the top for tickets, passports and keys; and then a larger compartment at the bottom for novels, my journal, and any medication, earplugs, or personal items that might need to be quickly accessed during the travel time. Stray away from bulky ones so you won't find yourself trying to cram it into a bin because the compartments let you pack too much.
5)
Obviously, get personal features that are important to you. If you travel with suits, a roll-aboard with a foldable suiter is a great feature, but it does take up precious space in the main compartment. A lot of companies are diverging out of the standard black colour for luggage -- so have some fun here!
The best constructed suitcases are made by Tumi, as has already been mentioned here. But you pay for it. I've always like Samsonite luggage, and I'm not complaining about my Connections bag either! Occasionally, stores such as Marshalls, Ross, or TJ Maxx will have great deals on Samsonite and other brands. Once you get past the technical stuff, the important thing is to find a bag that suits your needs. That doesn't always mean you need to dish out $400 for a suitcase; maybe a $79 special will do just fine. Mine has been going for 250,000 miles so far!
Hope that helps!

As you can see, I get pretty picky when it comes to luggage.
[This message has been edited by JohnnyP (edited 12-11-2002).]