Changangkha-Kuenselphodrang (Changsel Hike) has become very polar hiking trail in Thimphu. Actually, it's a biking trail which is part of biking trails around Thimphu city which was constructed in 2016 to commemorate the 60th birth anniversary of the fourth king, but its also an excellent hiking trail too.
This hike takes about 2 hours to complete and it can either be started from Changakha Parking and end at Kuenselphodrang (Buddha Point) or in reverse (Kuenselphodrang to Changangkha Parking. I would prefer the second option as it's a bit easier than the first one as there is less uphill hike. It's a beautiful hike through the mixed forest of blue pine, oak, rhododendrons etc, with an excellent view of Thimphu city on one side.
It is not advisable to hike alone as the trail passes through some thick forest and gorges too, so chances of meeting bears especially in summer.