The following trail description is largely provided by climbing associate who last climbed Audubon/Paiute in 2016. To keep mileage reasonable, save Mt. Audubon for when the Forest Service opens the road all the way to the two trailhead parking areas for Long/Isabel Lakes and Mitchell/Blue Lakes. The former we call the West Trailhead and the latter, the North trailhead. The road back to these parking lots may not open until June some time. If you have to start hiking from the east end of Brainard Lake, it will add another 1.5 miles to your day. For Audubon/Paiute, you'll want to park at the "North" parking lot. There are two trailheads here: one for Mitchell and Blue Lakes and the other for Audubon. The Audubon trail will be at the east end of the parking lot, away from the ranger hut and restrooms. Just read the signs to make sure!
Follow the well-used Audubon trail NNW. This old trail is very well-worn, many times rocky and sometimes deeply entrenched from use. In about a half mile, you'll begin to exit the trees as you approach timberline. You'll be staring up at a hillside of boulders. The trail turns abruptly east on a switchback and climbs more steeply for the next 300 feet with a couple more switchbacks. For photographers, our source advises that a ninety minute start before sunrise will place you in this location with an unobstructed view of the eastern plains and the emerging sunrise. After the switchbacks, the trail emerges from the last trees and gradually ascends in a NW direction. Stay left at about 11,280 ft. where the Beaver Creek Trail heads off to the north. Earlier in the season, you may have snow to deal with. Just below 12,000 feet, there are a few more switchbacks. At 12,600 feet, the trail flattens and comes to a col of sorts, just west of Pt. 12,706, affectionately named "Notabon." It has a wind-swept summit with at least one rock shelter. There's a great view north toward the Coney Lakes and into the peaks of Rocky Mountain National Park. The knobby summit of Audubon is another 625 feet of gain to the SW. Leaving behind the nicer tundra terrain, the main trail begins to fragment into multiple paths through all the rock. Just choose the best path that climbs up through the sloping, talus. A number of cairns may mark the best path. This last stretch is the steepest and most difficult and really the only part of this hike that deserves a Class 2 rating. From the col to the summit, you're likely to encounter windy conditions. The summit has several, perhaps as many as a dozen rock shelters people have constructed to block the high winds typical of a Front Range peak.
From the summit, you'll enjoy nice views looking down on Blue Lake, and of the high twelvers to the SW. The view to the eastern plains of Colorado is unobstructed. From here, either continue on to Paiute Peak or return by the same route that you ascended. If returning to the TH from here, many average hikers can complete this hike in about 5-6 hours.
Links to other information, routes & trip reports for this peak that may be helpful.