The Great Wall Box House

Although initially it seemed a bit pricey for a hostel ( map ), it was very clean and comfortable with lovely, pleasant decor and very good free dinner (food was simple but so tasty!). It was refreshingly different from your typical Chinese farmhouse experience. It's a quiet cute place with a great relaxing atmosphere. The waffles & eggs for breakfast are both very good! The staff are helpful as well.

Very nice communal bathroom area with a washing machine and dryer you can pay to use. The toilets have Japanese style heated toilet seats with bidet. There are 2 shower rooms. The water pressure was quite weak but the water was nice and hot. The beds are a bit hard but still comfy. You get your own locker.

It takes 5 minutes to walk to where you can get onto the Gubeikou section of the unrestored wall. It takes 5-6 hours to hike from Gubeikou towards Jinshanling then back. Make sure you listen to the hostel staff's directions before leaving and not to get lost getting down.
Our taxi driver had a bit of trouble finding the place. Instead of going on a road called GǔYùDào [ 古御道 ] which is the more touristy cobblestone street right before the tunnel, it's on the paved asphalt street before it called YōngJūnLù [ 拥军路 ]... so coming from Beijing, turn right at the 2nd street before entering the tunnel). Watch out for the metal sign on the left side of the road with drawings of cats on it. * Make sure you have their phone number before going because if you google Great Wall Box House, another hostel's phone number in the area pops up and they'll pretend to be it.
It takes 20 minutes to walk to the bus top where you can take Bus 25 to get back to MìYún ChángTú ChēZhàn [ 密云长途车站 ]. You can just swipe your Beijing Subway card. It takes about an hour. From there, you can take the 980 bus back to Beijing.