Mt Evans is great and more accessible than RMP to Boulder unless you like the Estes Park end. I think the best part of that road is the Grand Lake end. You can, however, get above the treeline quickly from Estes Park. Mt. Evans has Bristlecone Pines - the only place in Colorado that does.
But with only two hours, I might go to Colorado Springs and see Garden of the Gods. It's a city park, very accessible, beautiful in the morning, teeming with wildlife, and has lots of well known and not so well known photo sites.