For small trees, try Russian hawthorn, Amur maple, Shubert cherry, Callery pear, Japanese tree lilac and serviceberry. The same is true of plants. Carefully consider exposures for planting. North and east exposures are cooler than those to the south and west. Some plants will tolerate the hot afternoon sun of west exposures and others are best located in east facing locations that receive gentler morning sun.
Further help is available.
Visit local nurseries. Talk to neighbors about their garden successes. Read Colorado garden books and local newspaper garden stories. You have moved to a beautiful and unique place. Colorado's low humidity makes cold days seem less cold and hot days less hot.