First and foremost...you've made the trip all the way out there...shell out the pocket change to go inside the buddha. It's really interesting to see how such a large sculpture is constructed and after visiting hundreds of temples in my lifetime I've only ever been inside one buddha. There are a lot of kids on school trips in this site and of course, a lot of tourists (not just foreign ones). They have a great bookstall right near the buddha statue, so you can pick up some lit to improve your knowledge of boddhisatvas and symbolism. Also, don't forget to check out the giant straw sandals. All I know is that if they can make shoes that big, why can't I ever find any in my size?
Oh, and if you're traveling with a kid (or a grown man who thinks he's a kid) be warned that there is a really "cool" giftshop outside the temple selling weapons. You've been warned.
When I first went here I was unsure if this was a university lecture hall or a temple. But once you start paying attention to the details....oh wow. It is breathtaking. The architecture is amazing and reminded me of the great European cathedrals. You can see a variety of influences from around the world play out in the details of this temple. If you're in the area, you simply must stop by. But keep in mind that it is quite an active temple (actual religious ceremonies, not just coffee break prayer).
The approach is lined with stores and shops. This traditional shopping area/mall is just wonderful. When you think of traditional Japan and what you see of Tokyo in movies, this is what you get. Large temple grounds with a pagoda, beautiful lit walk for the evening.
If you can only visit one temple while you're in Japan, you should visit this one. This truly is a memorable site, and not just because of the serious number of people all in one place.
By far one of the best weekend retreats from Tokyo I've ever had. The train ride out there is pretty short and there are tons of hotels with both western and Japanese style rooms. The onsens in this area really are stellar. Just keep in mind that Nikko is not exactly a well-kept secret...places book up pretty far in advance. But if you go to JTB and get a lucky last minute booking, you can save a ton of cash on your trip, and still score an awesome travel package.