Extra day: Kawaguchiko or Nara?

I will be going to Tokyo and Kyoto in November for 12 days. I have an extra day with nothing planned, should I do a day trip to Nara from Kyoto or a day trip to Kawaguchiko from Tokyo?

I would say Nara, as it is quicker , cheaper and easier to get to.

Kawaguchiko is hit or miss. If the weather is fine you have a splendid view of Mt Fuji,
http://bicycletraveljapan.blogspot.com/2022/10/fuji-4-lakes-d1.html

if the weather doesn�ft cooperate there ain�ft any Fuji in sight.
http://bicycletraveljapan.blogspot.com/2023/06/ride-out-to-fuji-rain-a...

And yes, it is FAR easier to go to Nara than Kawaguchiko.

I personally would also choose Nara, however nothing wrong about Kawaguchiko as long as the weather is fine.

As others have said. Nara is the easily the best choice. So much to do & not dependent on the weather.

If you have some flexibility, you can use a combination of Live Cameras and checking the weather in Kawaguchiko (I recommend checking the weather in the entire region around Mt. Fuji in Yamanashi and Shizuoka) to determine if it's worth visiting. If it is early November, Kawaguchiko is more likely to have autumn foliage.

Kawaguchiko is a really great area and very worthwhile when Mount Fuji is visible, but if you cannot see Mount Fuji, it REALLY makes Kawaguchiko less enjoyable. Even if you have some fun, there is always the "it would be even better with Mt. Fuji" knowledge that weighs heavily on everything you do. I find this to be a big detractor for most Yamanashi travel...

Easy, Nara - wins hands down. Simple day trip from Kyoto or Osaka.
For me, Kawaguchiko really doesn't have enough on offer that you can get to easily.