Backpack into the pristine Thornton Lakes to set up a scenic basecamp before you scrambling up to Trappers Peak for more amazing views.
To get to your campground or to Trappers Peak, hike roughly five miles along the trail to ridge, where the trail divides. If you head left you'll go down into lake basis where you can drop your gear. Come back to the divide and head right, which will lead you up to trappers peak.
Something to keep in mind, the trailhead is unreachable for most of year. Best time to do this hike is mid-summer through fall. The forest road to trailhead is also pretty rough so a four-wheeled vehicle is strongly recommended.
To get to Thornton Lake trailhead, drive 11 miles north of Marblemount on HW 20 (North Cascades highway) until you reach a left turn for Thornton road. Drive ~5 miles on this road to reach trailhead. WARNING: four-wheeled vehicle is strongly recommended; forest road grade is quite steep at times with loose gravel.
If you're looking to grab a bite and a beer afterward, check out Train Wreck Bar in Burlington.