First destination is small harbor city Otaru. Old Canal, Kitaichi Glass factory and Musical Box factory are major tourist spots. Then head to Jozankei via Asari toge pass. You can enjoy autumn leaves here and take a gondola called “Koyo gondola” at Sapporo Kokusai before arriving in Jozankei.
Overnight in Jozankei

Enjoy autumn leaves around Jozankei/Hoheikyo area. Canoeing must be interesting here. Then go to Fukidashi park where you can collect spring water come from Mt. Yotei. About 1 hr drive to Lake Toya area. Stay in Toyako onsen resort and see fireworks in the night. Available till the end of Oct.
Overnight in Toyako

Why don’t you try fruits picking in Sobetsu town in the morning? Then head to Noboribetsu. Hell valley, Oyunuma, Date Jidaimura etc. are tourist attractions. National ainu museum called UPOPOY where you learn and enjoy Hokkaido native “AINU” is a new destination on the way back to Sapporo.