Day 1: Little Molas Lake to Elk Creek Trail, about 11 miles. See the narrow gauge railroad train making its 11:30 stop in Elk Park. Crossing the Animas river, it wasn't as big as I thought, but the trail is great. Most people are out there trying to bag Vestal Peak. Once you get past the ponds the population thins significantly.
Day 2: Elk Creek Trail over the Continental Divide to Beartown, going back up and over Hunchback Pass, and down into Vallecito Creek, about 16 miles. Passed a cool miner cabin and many mines, and the continental divide is reasonably easy to bag. Pretty quiet for the rest of the day. Vallecito would be nice except there is too much horse crap all over it.
Day 3: Vallecito Creek to Johnson Creek and up and over Columbine Pass to Chicago Basin, about 12 miles. Johnson Creek Trail is very nice all the way to Columbine Lake. I saw a herd of mountain goats in the distance past the lake. The worst part of this trip was Columbine pass. The trail is bad getting to the pass, and terrifying for about 150 yards on the other side. The trail is pitched about 20 degrees sideways and 15 degrees down. You are trying to place your feet on tiny scree pellets hoping your feet don't start sliding and you die falling into the gully to your left where you won't stop for at least 1000 feet. Once past this the trail gets better. It was quite crowded in Chicago Basin.
Day 4: Woke up to mountain goats in my camp. Took many photos, then climbed up to Twin Lakes and decided to climb Mt Windom, my first mountain peak over 14k. The toughest part is to control your pace and breathing, with the thin air. You want to go fast but the body will quickly break down on you if you go too fast. The trail gives out about 500 ft above twin lakes, but there are many cairned paths to choose from. It is a hike until you get to a large saddle, then the last 600 ft is class 2+ climbing over boulders all the way to the peak. After 300 ft of climbing there is a narrow saddle to cross, past this is where the physical effort really increases. The last 300 ft seemed to take 3 times as long as expected. Snow and lack of desire ended up with me deciding to not scale any more peaks. Rained at night for many hours.
Day 5: Down Needle Creek, along the Animas River and up Purgatory, about 13 miles This hike was relatively straightforward and the scenery was great. Heard a couple of trains pass by. Saw only one of them. It didn't seem hard but I was perhaps the most sore after this day.
Day 6: Up Purgatory, along unnamed trails and the highway, then up Cascade Creek and Engine Creek, about 11 miles. This was a lot of elevation gain but it is spread out except for a portion of Engine Creek that is steep. Took a side trip to see the falls along the cascade creek trail. Found a perfect campsite along the Engine Creek Trail with a picnic table, miles from anywhere. Nice way to finish off the camping.
Day 7: Up Engine Creek and Engineer Mountain Trail to the Colorado Trail, which I follow all the way back to Little Molas Lake, about 12 miles. Once gaining the elevation a bit of rain rolled through but it cleared up. Saw a bunch of marmots, and a ton of sheep at the end.
Most people do about half this loop using the train to get in to Elk Creek and Take out at Needleton. Given the cost and the reviews I've heard, I was glad to take the 2 extra days and do the extra miles to do this as a loop rather than take the train. I packed enough food for 9 days expecting the possibility of thunderstorms. Several days it almost turned bad but the weather stayed just good enough that I was able to stay on schedule. Lightning was the biggest concern, as I might not have be able to go over treeline, so best to plan for a few extra days. However, the pack is quite heavy with all that food. The first few days were a drag with the big pack.
I would recommend this loop to anyone, but halving it by using the train appears to be the more popular option you may also want to check out.