You're going on a trip, and need luggage. Did you consider your carry on luggage size? It's important to know what's allowed and what isn't. Obviously verify with your airline, but I'll give you some generally accepted carry on luggage allowances to help you shop.
As I stated in my carry on luggage article, weight is a factor. Some airlines have no restrictions when it comes to carry on luggage weight. Others are as low as 11 pounds, some as high as 40 pounds.
Most airlines will allow one piece of carry on luggage and one personal item. They consider a personal item as carry on. The weight is the total of the two. Personal items include a purse, laptop bag, reading material or another small (no bigger than 36") carry on bag. Keep those carryon luggage limits in mind when packing!
The standard carry on luggage rules are 22" X 14" X 9" for a total of 45". Again, these carry on luggage dimensions vary both by airline and shape of the bag. Even if your carry on luggage doesn't exceed the allowed dimensions, the airline can make you prove that the bag will fit by putting it in a box, and if it won't fit, your luggage will be checked.