Your biggest issue in the Denver area is that most of the flight schools tend hire from within unless you're really exceptional. Their CFIs often start there as student pilots and are ultimately brought on as instructors. They have already shown a commitment (and spent money) with the organization and are already trained in the schools procedures and methods.
There are a few smaller organizations where you can get in - but that would strictly be on an independent contractor basis - you develop your own student base, carry your own insurance; the "school" does nothing more than provide the airplanes with appropriate inspections and maintenance.
I'm not completely sure what rick means about being weather-limited though. For instrument training, the biggest limitation is that flyable IMC is limited as IMC in the Denver area does tend toward ice or CB. And late spring-summer afternoons tend toward CB and wind shear. But otherwise, it's hard to call 300+ VFR days a year "limiting" for GA.