I am not familiar with Greeley proper but lived in Boulder for 15 years and spent quite a bit of time in Estes Park where a good friend lived, and RMNP. I used to go into Estes all year round and I think only the very highest passes may still have a lot of snow unless they get a big storm this week. And I suspect you could still drive all the way across the park over to Lake Granby on the other side. Another spot I always heard about but never got to was Red Feather Lakes which would be close, I think Poudre Canyon might be on that route?

Black Canyon of the Gunnison is one of my favorite places, spectacular but definitely would be a drive.

Diana