When in Kathmandu, if you do not much time for trek. The best option to see Mt. Everest is joining on Everest Helicopter Flight to Everest base camp. 

It was just wonderful with amazing views of Himalayan peaks and dramatic landscapes of high rolling green hills to arid and barren terrain.
A great moment to experience being close to Mt. Everest and having breakfast at Everest View Hotel made the trip more enjoyable and exciting.

Patrick Sullivan.