Here are some of the events in Nov/Dec. The dates are in 2017.
1 Nov- White Lovers Park Illumination
3 Nov- Sapporo Factory Christmas Illumination
24 Nov- Sapporo White Illumination
25 Nov- Sapporo Christmas
8 Dec- SWEETS Dream Illumination
11 Nov- Otaru Snow Story
11 Nov- Yoichi Snow Story
1 Nov- Blue Pond Lightup and Shirahige Falls Lightup
11 Nov- Asahiyama Zoo
2 Dec- Asahikawa Machiakari
11 Nov- Toyako Onsen Illumination Tunnel
Your itinerary is good for some of the big festivals in Sapporo and Otaru. Most are rather focused on illumination. It might be better to consider to go skiing or skating in the daytime.
Here are some of the nearby ski resorts. The opening dates are in 2017.
17 Nov- Sapporo Kokusai
21 Nov Sapporo Teine
23 Nov- Kiroro (day trip from Otaru)
25 Nov- Rusutsu (day trip from Sapporo)
23 Nov- Niseko Gran Hirafu
25 Nov- Niseko Annupuri
1 Dec- Niseko Village
22 Nov- Furano
8 Dec- Mt Racey (JR Yubari)
Both Sapporo and Otaru are well connected with Chitose airport. In this regard, you had been better to place these two at the two edges. Just I think of a kind of a sandwich itinerary, such as Otaru-Biei-Sapporo or Sapporo-Niseko-Otaru.
For more local information, take a look at bus timetables in Sapporo and Otaru cities and restaurants there.
http://www.hokkaidox.com/en/hokkaido-bus-pass/https://tabelog.com/en/hokkaido/rstLst/?utf8=✓&maxLat=43.107313...https://tabelog.com/en/hokkaido/