Local buses or tourist buses can be an alternative way to travel in Nepal or simply to get around Kathmandu. However, it may be difficult for you without a tour guide or if you don't know Nepali people to get around, but you can always find someone to help you, as the locals are very helpful.
Traveling by bus in Nepal can also be an adventure in the sense that most of the time the buses are rather old, there is not necessarily air conditioning and the roads are often under construction. You will have a hectic journey but this can be part of the Nepalese experience.