The first book is called Mandala Magic which is packed full of different kinds of mandalas. Mandals are great as they use repeating patterns to make up the space it is within, which usually is a circle.
The second book is called Secret Tokyo which is full of different sorts of imagery from Japan. With the kimono pages and even the tea page I could not pass this up. This same company does other places such as New York City.
Now let's look at some different types of materials. There are so many out there but here are a few that I suggest you give a try with your coloring books.
Pencil CrayonsWhen we were kids this was the upgrade we longed for once we were a bit older. They are great as you can layer different colors on top of each other lightly to (create more dimension or) just broaden out the colors you have.
WatercolorsIt is quick to use but you can really get more dimension put into each page you work on. The other great thing about this material is that you can also find portable palette with all the colors with it. Just add a collapsible brush with a water barrel and you can paint any where you may be.
Chalk PastelsNow for this one you will need some kind of fixative to keep your coloring in place which you can pick up at your local craft or art supply store for under $15 (or use hair spray as a last resort). This one it super fun as you can really build up layers to get the depth you want. It would be a great choice even as a base which you use another material over top (pencil crayons for example).
MarkersThere are so many other types of materials out there that you can try. If you are worried about bleeding through (which happens with markers) either get the picture copied and printed on a thicker paper or place some papers under the page you are working on. The last point will still allow for bleed but the second page will not be affected.
Have a favorite coloring book your would like to share? Share your suggestions in the comments below.