It's always a good idea to provide short-term entertainment for the little ones at your wedding, especially during mealtime. Even if it's as simple as providing something to color on and with, the parents will appreciate your thoughtfulness.
I love these cute chalkboard place mats for the kids at your wedding. They would be great at an outdoor or Colorado mountain wedding. Another simpler and more inexpensive twist on the idea is to use colored paper that matches your color scheme and supplying crayons or colored pencils.
There are many great options for creating your own coloring/game book, as well. A google search will lead to you to some ideas for personalizing your own wedding-themed kids' activity book.