If seeing Mt. Fuji is on your "must see" list, it certainly is worth a long day's tour from Tokyo. For us, most of the best views came from Hakone Park, which itself was interesting and stunning with it's cable cars, hot springs, etc. Weather is the most important factor. We were told that in September, one typically can see Mt. Fuji only about 12 of the 30 days, so we were quite fortunate. The wetter summer months offer even less viewing probability, while the colder winter months offer the best opportunity by far. When in Tokyo, consider this unique day trip.