As Alec mentioned, Colorado offers excellent opportunities for both nordic and backcountry skiing. For nordic skiing, ie mostly undulating trails and roads, you'll want a nordic ski setup. IMHO, the 'best' skiing in Colorado is the backcountry glade skiing (just below treeline). For this you can use either Alpine Touring (AT) or Tele gear. If you're currently an intermediate downhill skier, then you could probably ski the glades immediately on AT gear. If you swap to Tele gear, there will be quite a learning curve (maybe a couple of seasons) before you can weave your way through a steep glade in knee-deep powder. My advice would be to give serious consideration to a lightweight AT setup.
It's the same weight as Tele equipment, you'll enjoy it immediately, it will be easier on your knees and it will be superior for spring skiing above treeline. AT gear has a significant following in CO, partly due to the early efforts of Ramer. Lou Dawson, who grew up skiing in Aspen, is also a proponent of AT gear and has a website at wildsnow.com . It might be worth checking the equipment lists there, and posting equipment questions on the wildsnow forums.
I also recommend that you rent several different brands of gear before you buy. You can rent high quality gear at some of the resorts and also at specialty shops such as Neptune Mountaineering in Boulder.