Have you made sure you have a strong enough antenna? They are rated for different distances so you have to make sure its strong enough to get the signal from Denver. Hills, valleys, etc all play a roll in that too. I tried a 40 mile one from my house in Castle Rock and it was Ok. Used the same one at my parents in Highlands Ranch and they got like 50 channels and all came in clear. It was just about the better proximity and I live in sort of a valley.
The wife and I eventually want to do a whole house antenna and have it professionally tuned.