If short of time, skip Kathmandu and Patan Durbar Square. Bhaktapur is by fair the best in terms of layout and cleanliness. Entrance free is the highest at Rs1100 as compared to Rs750 and Rs500 respectively.
People are friendly and helpful. Decided to go on own instead of engaging a tour guide. It's not a money issue. At other places, halfway through the tour, we were taken to shops where the tour guides were given commission of sales. Valuable time wasted at such places.
Overall the ground is pretty extensive; requires at least 2 hours to cover the several temples. Must visit this temple.