Kathmandu has for long been one of my favourite places. I tend to stay in the Thamel area, which is the oldest part, but also now the tourist area. This means that you are well cared for in terms of hotels, guesthouses and restaurants etc, but with a large local population residing there as well, there's always plenty going on, and so plenty of photo opportunities. The people, like most Nepalis, are unfailingly friendly and courteous, and so photography is never a problem with them.