There are many sights in the Kathmandu Valley. We went on a 1-day whirlwind tour organized by our travel agent ($6 per person). We had a car and driver to bring us to the sights, but the driver was not a guide.
First, we went to Monkey Temple and Bodhanath. It was interesting. After that, we went to Bhaktapur. Bhaktapur was a UNESCO World Heritage Site that actually had people living in it. It was very impressive!
It did help if you had a local to bring you around Bhaktapur. In our case, our driver brought us around the back lanes, and we got to see how the Newari people live and how their houses look. We also saw the pottery-making process at the Pottery Square. Bhaktapur is also famous for its handicrafts, especially wood carving.
We went to Patan after that. In my opinion, Patan is overshadowed by Bhaktapur. The sights are more or less the same, but Bhaktapur was far more impressive. We returned to Kathmandu to see Durbar Square at the end of the day.