For nature in Colorado and New Mexico, I'd say look at the northern NM and SW Colorado. Several neat and different areas to draw your interest. Some of my fav's from that general area that offer scenery/hikes/day trips/etc in fairly close areas.
Great Sand Dunes NP
Ridgway/Ouray great base to take forest service roads to hikes or views of the San Juans
Rio Chama country in New Mexico
High country around Red River Angel fire is scenic
Bisti Badlands
Chaco/Mesa Verde for historic landscapes
The best part is all of these are only a few hours apart. On the other hand its a full days drive from RMNP to Ouray.
Check out the Rocky Mountain forum on Nature Photographers Network (some of the posters here are regulars there too) for alot more info as well as location info.
Have fun!
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