I went on a luggage spree last year, finally buying practical, colorful luggage in a variety of colors and styles. I got:
-two red Samsonite hard-sided suitcases with wheels, one extra-large and one presumably small enough to use as carry-on
-a red canvas weekender bag, which is even better as carry on because it hold SO MUCH and really does fit in the overhead bin.
-a brown nylon 2nd bag, which works great as the one to tuck under the seat. It has three pockets so I can fit food, magazines, electronics and my actual purse in it, and then it folds up easily into my other bags when I don't need it anymore.
These 3 bags have improved my traveling experience tenfold; I had to run 20 gates last weekend to make my connection in Dallas, and I slung that weekender bag over my shoulder and HAULED DUPA to the gate... and in a dress and boots! I made it with literally two minutes to spare. I could not have done that with a roller suitcase.
