Nikko is a beautiful area. The World Heritage sites are all within easy walking distance from each other. There is a bus specific for the sites as well. I took the train from Asakusa, Tokyo and used the World Heritage Pass. It covers the roundtrip train ticket on the Tobu line and entrance to the sites. It doesn't however pay for special exhibits within the sites. The buildings were beautiful and very peaceful. Toshogu had construction and renovations going on but the main gate and buildings were visible. I would recommend going as early as possible to the sites. Since Nikko is a very popular destination there are many tour groups as well as school trips there. After around 9:30a.m., the temples and shrines lost a little of their tranquility and became more of a circus. But overall I would go back here again and recommend it to others. There is more to the area than just the World Heritage sites. Nikko is also in a national park with hot springs, waterfalls, hiking, and a large lake. To do both the sites and the park will require a stay overnight as the natural areas are at least an hour away by bus. Also Nikko is famous for yuba (tofu skin) so try some of the great yuba cuisine while you are there.