The Aspen Trail boulders are great for summer bouldering, probably the best in town. A good summer day can be had by climbing at the AM/PM Wall in the morning, heading over to the Mango Boulder in the afternoon, and finishing the day off at the River Boulder. This will keep you in the shade all day.
If you haven't been to this area of Mount Lemmon yet, it's well worth the trip. Beautiful area, a stream, trees, and lots of bouldering potential, in addition to what has already been documented.
Again, if anyone else has route or area info that can provide more details, names, ratings, etc., please contribute what you can.
Drive to the end of the road past Summerhaven (Summerhaven Road). Park there. All three walls are within 15 minutes hike of the parking lot.
Mountain Project's determination of some of the classic, most popular, highest rated routes for Aspen Trail Boulders: