Just went with a private tour group (which you can arrange for at least 5 people at $15/person.
I knew nothing about how sake is made, and it was interesting to learn about how it's done and see the brewers at work. They start a new brewing process every two months. The staff explained how sakes are made, how the process works, and we tasted three different types of sake. I've only previously had the hot stuff that sushi bars served, which really tastes mostly like rubbing alcohol - I came away from Izumi with an appreciation for the complex flavours that sake can have, definitely an interesting experience worth the price of admission.