The size of your luggage will depend on where you're going and how long for. If you're just heading away for the weekend, a holdall, cabin case, or duffel bag is sufficient. However, for longer trips, a suitcase is more likely to serve your needs. The ideal size for checked luggage is between 25-30-inches tall, as this should keep you within the weight range and be easy enough to move. Of course, destination plays a role too. You'll probably need more room for bulky clothes if you're heading somewhere cold, whereas swimmers take up less space when heading somewhere warm. Preferably, you'll choose the smallest size your comfortable with. This will keep you under the weight limits, remove the temptation to overpack, and still be maneuverable. Having a few different suitcase and bag options will make this easier.