Kendwa beach has one of the most beautiful sunsets in Zanzibar. It is a large sandy beach with crystal clear water never influenced by tide. You can swim all day long. However, its a public beach so if you are not fan of crowd and beach boys than this is not a place for you. Its enough for one day trip to check the sunset and maybe party at some of many bars there.
Also if you need a reliable taxi services please get in touch with guy called Madiba (+255777109284). Very friendly and amazing guy who could help you move around for fair price comparing to others.