Sounkyo Onsen or Asahikawa Onsen 1 night

Hi
im planning to spend 1 night in Sounkyo Onsen or Asahikawa Onsen. Will arrive around midday and leave aroun 09.00 next morning. Wanted to see if anyone has been to these places and if so is it enough time to see anything (will arrrive by bus from Asahikawa, train from Sapporo unless a quicker way) and lastly which one of the resorts is the best one to stay in and to see best scenery? If we can stay for 1 night extra would this be recommended?
Many thanks for any advise!

There is no Asahikawa Onsen. Do you mean Asahidake Onsen? I am going to assume so.

is it enough time to see anything

Yes, at either resort, you can take the ropeway up, walk around a little and take the ropeway down again. Sounkyo also has some nice waterfalls a short taxi ride away. Asahidake has some walking trails. If you arrive around noon, you have enough time to enjoy the area a bit.

which one of the resorts is the best one to stay in and to see best scenery?

Both resorts come with noce scenery. Asahidake Onsen is considerably less developed than Sounkyo. Sounkyo is located in a steep, narrow valley, while Asahidake is surrounded by rolling, forested mountains.

More details:
http://www.japan-guide.com/e/e6775.html

If we can stay for 1 night extra would this be recommended?

Unless you want to make a major hike or relax some more, more time is not really necessary.

Thank you so much for your reply. We have such limited time in Japan and trying to make the most out of it without hurrying too much.
I think we will go to Sounkyo Onsen. Is it far to walk to the waterfalls there?
Next day we will head for Lake Toya, I saw your reply to my other post which helped alot.
Many thanks!

Is it far to walk to the waterfalls there?

It is about three kilometers (45 minute walk) one way from the town center to the waterfalls.

That sounds good.

I'd better start booking the accommodation :)

Note that the walk to the waterfalls is along a busy road.

Are you taking trains or driving?
If you are using public transportation, just to let you know that some hotels in that area provide free shuttle service to customers from Asahikawa.