There are so many online printable coloring pages that you can have a blast offering them to your children. Perhaps you don't have children of your own but you often have friends and family that come over with their young ones. You don't want the kids to be bored at your house. Allow them to pick some coloring sheets that you can print for them. Have crayons and other supplies on hand for them and they will feel very welcome in your home.
With online printable coloring pages you never have to keep volumes of coloring books around. Most children change what they would like to color often. They bounce around from one theme or one set of characters to the next. Therefore they may abandon that coloring book with princesses or cars days after you buy it. Printing out the pages though allows them to always get what they want.