Mt. Fuji

Hi,
This entirely depends on your interests. Going to Mt Fuji itself, there is nothing to see since you are on it. But in summer some people climb the mountain to the top, especially to see the sunrise.

The two main places people go are to Hakone
and the Fuji 5 Lakes. Each has good views when the weather cooperates and their own local sights - there are similarities but are not the same. Choose which ever suits you better. An Odakyu pass can save you money for one or for both.

Good luck.