A racquet bag can make your trips to the court or gym a little more convenient.  Bigger bags can make away tournaments easier, by allowing you to pack all your gear and clothes for the trip in just one bag.
 
The links below will take you to racquet/gear bag pictures for those brands.  Here you will find descriptions and sizes for each most bags shown.

Black Knight

Head

Karakal

Tecnifibre

Babolat

Manta

Prince

Yonex

Dunlop