At Durbar Square many holy men will ask you for money to take a picture. A true holy men won't ask you for it.
Many small villages, like Bungamati and Kokhana, are worth visiting. You can walk from one to another, it's only one hour or so. Interesting sights and friendly people will welcome you, for sure...!
My suggestin to stay on the beaten track in this country as its bloody cold and its easy to get lost and die from the exteeme cold.
When in Kathmandu, you should explore the city to have a feel on the actual daily life. Although the city is dusty, lively and chaotic, it is quite safe to walk around.