Kyoto Day Trip

We are visiting Japan in July and will have 4-4.5 days in Kyoto. We are also visiting Tokyo (4 nights), Hakone (1 night), Osaka (1 night), and trekking the Kumano Kodo (3 nights).

We'd like to do 1 day trip from Kyoto. We are not interested in Nara. We were always planning to do Hiroshima and Miyajima, but then I came across Naoshima. I realize that it is a bit further away, but we like long train rides. :) It just looks like such a unique and cool place, so now we are very torn.

Please help us choose! Thank you!

If until June.
There seems to be a day tour from Osaka.
Namba 6:30, so 7:00 departure from Shin-Osaka, it is possible to go if dere to 6:00 Kyoto.
http://www.bus-bus.jp/naoshima/plan/osaka/en/
There are a few from Kyoto.
http://www.bus-bus.jp/naoshima/plan/kyoto_kobe/
Maybe, because there is the possibility that the period will be extended, please check.
Please check here the time of the train.
http://www.hyperdia.com/en/
Route to Naoshima
http://www.benesse-artsite.jp/en/access/index.html
It is better to go by Shinkansen to Okayama Station from Kyoto Station.
Shinkansen of 5:44 Kyoto station, get to 8:24 in Uno station.
Shinkansen of 6:56 and arrive at 9:10 to Uno station.
Maybe, it is easy to crowded because it is summer vacation from July 20 .
Naoshima
http://www.benesse-artsite.jp/en/access/map_naoshima.html

Thank you - so you would recommend Naoshima prior to July 20?

And what about Koyasan... a unique place in Japan!http://www.soleilrouge.org/koyasan-presentation-generale