Here is a list of trees that I recommend for the Colorado front range.
In 18 years of working on trees in Colorado, I've observed many trees in all types of growing conditions. Based on all these factors, I have a list of personal favorites that do very well in our soil and climate conditions.
The TOP of each category will be the largest trees. The BOTTOM of each category will be the smaller trees.
THE SPRUCES:
Blue Spruce - Picea pungens

Engelmann Spruce - Picea Engelmannis
THE FIRS:
Douglas Fir
White Fir - Abies Concolor
THE PINES:
Ponderosa Pine - Pinus ponderosa
Austrian Pine - Pinus
Lodgepole Pine
Limber Pine
White Pine
Foxtail Pine
Bristlecone Pine
Pinyon Pine
Mugo Pine
THE BROADLEAF TREES:
Norway Maples
White Oaks
- Burr Oak
- Chinkapin Oak
Northern Red Oak
Catalpa
Linden
Horse Chesnut
Kentucky Coffee Tree
London Planetree
Eastern Redbud
Plums
Peach
Callery Pear
Cherry
Canadian Red Cherry
Hawthorns
Ginala Maple
Rocky Mountain Maple
Golden Raintree
THE CEDARS & JUNIPERS:
Eastern Red Cedar
Atlas Cedar