20 – 30 mile loops in Colorado

Here are a few options
http://www.pmags.com/backpacking-loops-%E2%80%93-mags-favorites

The Pawnee-Pass loop is esp. nice.

There are others too I enjoy, but those five offer a nice sampler.

Four Pass loop is very strenuous and is 5 hours from Denver. The Goose Creek Trail loop in the Lost Creek Wilderness would absolutely fit the bill for everything except the fishing. It's about a 26 mile loop.

Here is a detailed Trip Report that I referred to when I first did the loop

http://www.14ers.com/php14ers/tripreport.php?trip=8128&parmuser=Derek&cpgm=tripuser

Here are some more pictures to wet the appetite

http://39degreesnorth.net/blog/blog/2011/07/31/lost-creek-wilderness-goose-creek-trail/

If you are interested and would like a full GPX file I can send that. Note that this isn't an easy hike either with about 7000ft of elevation gain in that 26 miles. I would recommend doing this in 2.5 days if you want to take a more moderate pace.

Awesome list so far. I could use some more ideas for this, too. Anyone else?

Buffalo Peaks Wilderness.

There is a valley hike linking together Rich Creek Trail, Tumble Creek Trail, and Salt Creek Trail. Complete loop travels all the way around the Buffalo Peaks and is 20+miles. Close to Denver, Fishing in various Beaver Ponds, easy hiking without significant elevation gain. Relatively high altitude hiking in the 10,000-11,500 zone. To get there you take Highway 285 South of Fairplay. Turn West on CR 22, follow to Rich Creek Trailhead.

You start at the Rich Creek TH and proceed west along the Rich Creek Trail. After about 6 miles you will come to the convergence with the Tumble Creek Trail. You can proceed south and eventually back East as you circle West and East Buffalo peaks which are 13k ft peaks that the wilderness is named after. I haven't been on this southern segment of that trail but the USGS map shows the trail distinctly. You eventually catch the Salt Creek Trail which takes you back to the North to rejoin the Tumble Creek trail and eventually back to the Rich Creek TH. Personally, I think this is the very best option considering your companion that is recovering from Back issues. The trail is very well defined and the elevation gains are modest and hiking very scenic.

Thank you to everyone for your suggestions. Randy, special thanks to you for your thoughtful and thorough replies! I really appreciate your input. You've given me several options to consider, but this last recommendation seems to have all bases covered.

I'm considering trying to do the LCW loop this weekend. Any insight into the trail conditions this time of year? The Rangers say the lake park trail has a lot of fallen trees. The guy in the report you provided went in early June and found lots of fallen trees, but little snow.

I'm just wondering if the trail would be considered impassable or just difficult/tedious due to the conditions. I'll be traveling with some friends for whom the impassable bar might be considerably lower.