I do have several pieces of luggage from Samsonite, to Delsy and a couple Lesportsac and Kipling.
The most important feature for me is light weigh. I cannot handle a heavy bag ( with the exception below).
For traveling for 4 days or less, with luggage I won't be checking in (primarily when I travel by road), I take a 2 wheel bag by Delsy. This bag is carry on size but I have checked it in. For traveling of 4 days or more or traveling with a bag I will be checking in, for sure, I have a Samsonite bag. This one is heavier and a bit bigger.
My luggage is old and I cannot longer find them online.
I do have a number of duffles and other bags that I take for overnight trips etc. Those are usually taken in addition to the two above and would not use them as my primary bag. I cannot hold on to those bags for extended periods of time. My bags need to ROLL.
Choosing luggage is just like choosing a handbag. It all depends on what you value most. My luggage needs to be lightweight so that's what I go for. With the exception of this cutie:
http://www.target.com/p/alice-.....medium_1_4
Weights a lot, but what a cutie pie.
For the type of traveling you will be doing I would go either with a wheeled backpack or a very lightweight carry on size bag. 4 or 2 wheels is actually pretty indifferent to me.
ETA: To Gaylene, I love those Lesportsac duffles. I have two! I love to take them empty inside my luggage to bring back goodies!
ETA2: And I don't buy sets. I only travel with one piece of luggage, no exceptions.