Ason/Basantapur Favourite time pass Junction it's always busy area .
Shivapuri - Favourite place for hiking with my old buddies from Nepal.
Nala/Nagarkot - Best places in kathmandu to spend few days peacefully away from those dust and garbages.
Patan Areas - Great places to get local home made wines . Few months back i went to Nepal was in kathmandu for almost 15days every evening i spent time in Patan /basantapur .

Couldn't make everywhere since i was in short vacation and got busy meeting friends and family most of times.

By the way @ main topic One day won't be enough to take sneak peak at Mt.Everest and get back to KTM atleast give it 2 days time . I had same plan but couldnt make it there but next time if i ever plan to go back i will atleast take 3months Trip to go all around best places in Nepal.

Be sure not to get fooled by many people out there ....since you are planning to go with Tourist friends Taxi Drivers will try to make maximum money through you . Be ready to deal with them i had almost got in fight with some of them they were pulling my bags .

Lastly No i don't play FPS.