asking for onsen

hello!

My friend and I will travel to Japan next march. This will be our virgin trip to Japan and we are looking forward to explore the awesome japan during our travel.

We will have 11 effective days in Japan and based on our itinerary, those are still not enough! We already making plans for the next trip (to compensate those places we are not able to visit to.)
The problem is: We have 1 last free day in our itinerary, and we both now wondering how to spend the day.
We actually planning to visit hakone or kusatsu and have an onsen experience, but due to the time constrain (only 1 day), we begin to doubt our plan..

I just want to ask, is there any recommended onsen to visit in kyoto/hiroshima?

thankyouuu~~~

There are a few near those regions, but no really good ones within those cities themselves.

The one off the top of my head is Arima Onsen in Kobe, which is in between Kyoto and Hiroshima and is pretty easy to access:
http://www.japan-guide.com/e/e3558.html

There are others listed on the following link, but I think they would be more out of the way.
http://www.japan-guide.com/e/e2292.html