Visiting Hiroshima

Hello there. I am planning a 10-day trip to Japan in the end of December this year. I have personally been to Japan many times now, but this time I am bringing my cousins along and it will be their first time visiting Japan. They are interested in visiting the traditional side of Japan, so I am thinking of basing our trip in Kyoto and Osaka. We will be spending a few days in Kyoto (2-3 days) and another day in Mt Koya. We will also be around Osaka for 1-2 days.

I am thinking of bringing them out of Kansai to visit other places as well. I am deciding between the west side (Hiroshima, Miyajima, Okayama) and the east side (Takayama, Shirakawa etc). We will only have about 3-4 days left and I'm not sure which place would be more suitable for us. I am aware that it is a long journey to get to Takayama and Shirakawa, so I'm leaning towards Hiroshima. But I would like to hear your opinions about this matter.

Another question: I would like to bring them to a hotspring town, preferably somewhere more traditional. I've been to Kinosaki and I absolutely loved the place. I don't mind bringing them there again but I was wondering if there are other hotspring towns around the area that you guys would recommend.

Thanks. :)

Visiting Hiroshima is a great idea. Going to Takayama is fine as well, although as you said it does take time getting there. You can get a taste of it much closer though by going to Miyama just north of Kyoto City:
http://www.japan-guide.com/e/e3985.html
But heading west there are more varied places to see overall.
Seeing some places you've been to is fine, but it's also great for you to cover some new ground as well to avoid getting bored.
There are numerous possibilities for you - seeing Hiroshima/Miyajima is one, also Okayama has Korakuen, one of Japan's finest 3 gardens:

https://www.youtube.com/watch?v=5zAI3_N7NEM

Plus Handayama is very beautiful there as well, in addition to the castle:

https://www.youtube.com/watch?v=JGQ8o7k9GbA

Visiting Kurashiki is another possibility, as is Onomichi - and don't miss Kosanji:

https://www.youtube.com/watch?v=97Q5EjEOXI8

A couple of other off the beaten trail places are Konpirasan in Kagawa, a splendid half day hike:

https://www.youtube.com/watch?v=ley9rVIewoQ

As well as Iwakuni, just 20 minutes or so past Miyajima:

https://www.youtube.com/watch?v=0COOZXi66mM

And if you really want something mind-blowing, go visit Akiyoshido in Yamaguchi:
http://www.japan-guide.com/e/e6130.html
If you are looking for hot springs, they are just all over the place. But since you are planning to go see Koyasan, there is nearby Shirahama which might fit the bill nicely:
http://www.japan-guide.com/e/e4958.html

Yubara Onsen is a great rotemburo (outdoor, open-air onsen). The town itself is very small and there are a few other areas that make up Yubara Onsen along the bus route where you could stay if you prefer, as well.

http://www.yubara.com/

Thank you so much for the quick replies!

Kurashiki and Onomichi captured my attention the most by far. I'll definitely be checking that out!

Yubara Onsen looks amazing too! Maybe we'll pay that place a visit instead Kinosaki. :) Thanks!