Your best bets are higher elevation (9500 ft+) areas that are more sheltered from the wind that can come off of the Continental Divide. I wasn’t able to get to everywhere to check (busy week), but also consider Gem Lake, Bear Lake and past Alberta Falls, and on the west side, Timber Lake, - let me know how it is!
The aspen near the Alluvial Fan and Beaver Meadows have yet to change. The area around Lily Lake and the drive along the Peak-to-Peak highway is really past-peak and most of the leaves have blown away. It’s not too attractive for leaf-peepers right now.
Timber Lake Trail – - the aspen on the west side change a bit sooner than the east, but are also a bit more sheltered from wind. Timber Lake Trailhead has some great stands of aspen nearby, and through 0.7 miles up the trail. Unfortunately, our map doesn’t include all the aspen here – the distrubances that made space for them are more recent. The Kawuneeche Visitor Center is a also a good stop.
Bierstadt Lake Trail — This area should just get better in the coming few weeks, and the aspen groves across the valley are still quite vivid. This hike is quite exposed and steep – try to do it in the morning or late afternoon.
You can find more features for making the most of the aspen season with the Afield Rocky Mountain app.
Natural History Wanderings has a great collection of sources for fall foliage locations around the country. It’s also a great website for information on birds, wildflowers, and nature photography.
The Coloradoan’s 2018 fall colors guide covers all of Colorado and is updated weekly with reports and links to other resources.