Nagarkot is the nearest Himalayan panoramic view point to Kathmandu and can be easily reached in under an hour (traffic permitting, of course) from Kathmandu. No doubt about it, clear views in particular are exceptional. From this wonderful vantage point, it is sometimes possible to see from Dhaulagiri in the west as far as Kangchenjunga in the east. That's around 300km of Himalayas!
The very keen eye (and usually with the aid of powerful binoculars) just might be able to pick out the summit of Everest, although it is only a pinprick on the distant horizon.
So, no prizes for guessing that the main reason people visit Nagarkot is to view the sunset and sunrise. Nagarkot could be described as a mass of hotels and guest houses clinging to the rim of the Kathmandu Valley, all jockeying for potential viewing positions. Certainly, of the number of times we've been up to Nagarkot, more than half of the time we've also enjoyed the thrill of being above a sea of clouds. That is seriously cool. but we can't promise that. I wish we could, though. By the way, the fresh air up at Nagarkot is just that—fresh!
At around 2000 m, it's noticeably cooler up here (especially at night) than down in the valley below, and it can get very windy too.
We'd suggest that one night at Nagarkot is enough if your reason for coming here is for the views.
There are also some very nice ridgeline day walks to enjoy, and although Nagarkot itself isn't a traditional place, once you're out of Nagarkot (and it's not a big place), you have rural, hilltop Nepal to enjoy, as well as those views to accompany you too.
Our short Kathmandu Valley Skyline Trek is a nice way of incorporating a visit to Nagarkot. This short trek affords extensive panoramic views of the Himalayas as you walk along the rim of the Kathmandu Valley to ultimately descend to mediaeval Bhaktapur.
You could also consider Nagarkot as an alternative suitable final location for your custom Nepal visit instead of Kathmandu. Time wise to the airport, it's almost the same from Nagarkot as it would be from central Kathmandu and with clean, mountain air and views a nice final memory of Nepal.