A duffel bag is a classic choice for overnight luggage buyers. This type of bag tends to be fabric and handheld, with the option of a shoulder strap. They do not have multiple compartments --- instead, you just put everything inside and zip the bag. They are available in many colors, and while fabric is an economical and widely available choice, they are also found in leathers and decorative materials.
A camping-type backpack is an option for overnight luggage, especially when you're going to need to carry it for long periods, and of course when you're actually camping. These backpacks are large, and in addition to traditional shoulder straps also strap around the midsection for extra support. They have plenty of space and can even be found in waterproof materials.
Rolling luggage is great when you have to go through hotels or airports and have to move around a lot. This kind of overnight bag tends to be a miniature version of a suitcase and has wheels and a handle that retracts and expands for added comfort and ease in transportation. The bags normally have one main large compartment and a pocket or two on the lid.
For the times that you want or need to be more fashionable there are now oversized tote bags that are made to be overnight luggage. While the bags look stylish and put together, they have the space and durability necessary for traveling overnight. These come in many fashions, colors and fabrics, making it easy to find the best one for you.