If you wish to do scenics, in the Eagles Nest Wilderness area (between Silverthorne and Kremmling is a beautiful natural lake on the southwestern side of Green Mountain Reservoir. To the southwest of that lake (Named Lower Cataract Lake) is a mounstrous waterfall coming down the hillside. If you are so inclined you can find the trailhead nearby (the name escapes me now) which will take to up the mountain past Tipperary Lake and upward to Upper Cataract Lake. This is an awesome scene with the lake at 10,600 ft elevation but at the southern edge is a 13,600 ft rock headwall. This is a tough climb and is well worth the effort if you want an awesome photograph.
Another area is in Glenwood Canyon of the Colorado River. There is a trail leading to Hanging Lake. Another hiking trail of several miles, although not as extreme as the trail to Upper Cataract Lake. This is a beautiful site with the lake seemingly hanging at the end of a canyon.
Another area is south and west of Leadville in the Collegiate Peaks Range. This would be on the highway to Aspen Colorado (closed during winter). Many incredible photo opportunities along this drive. Once over Independence Pass, you will encounter the drainage of the Frying Pan River and there is an area that is known as the Grottos. Also an area known as Lincoln Creek. Many dense aspen stands immediately south east of Aspen.
Then there is the area south of Carbondale along the Crystal River. At the town of Marble you can drive the road to the largest marble deposit and quarry in the world. The well known and photographed Crystal Mill lies between Marble and the Crystal townsite.
South of Breckenridge Colorado over Hoosier Pass is the town of Alma. To the north and west of Alma (up the mountain by road) is a stand of Bristlecone pine trees. Sobering in the realization that these existed before the time of Christ.
These are obviously all best photographed during the summer months. I have many more suggestions, if you have already photographed these. However these are all within a day trip from Denver. Good luck and have fun.