Your preference? For me, it looks you allocate too much time in Sapporo. There are many places that could be done by a day trip. Hokkaido X summarizes such candidates with maps, timetables, and sample itineraries.
http://www.hokkaidox.com/en/hokkaido-bus-pass/https://www.youtube.com/watch?v=1GJ6qyycYrchttp://www.hokkaidox.com/wp-content/uploads/2017/08/b6db663c9be20b191a...http://www.hokkaidox.com/wp-content/uploads/2017/08/9715906b703637f795...Here are some December recommendations by four companies.
Biei Blue Pond, if the day should be sunny.
Wakasagi, smelt, fishing in Lake Shinotsu. It could be opened as early as 20 December.
Mt Moiwa has its own sky area. Night skiing is also available.
Sapporo Factory Christmas is an in-door illumination facility. There are five-minute special showtime events at each hour from 16h to 22h.
Hakodate Illumination.
http://ikedanaoya.com/spot/post-11803/Illuminations at Sapporo, Asahikawa, and Monbetsu.
Hokkaido Gishi Festival at Sunakawa on Dec 14.
Asahidake with snow.
http://www.tabirai.net/sightseeing/hokkaido/info/monthly/dec.aspxMunchen Christmass Market in Sapporo.
Hakodate Christmass Fantasy in the Redbrick Warehouse area.
Biei Blue Pond & Shirahige Waterfalls Lightup near Shirogane Onsen.
Tancho, a Japanese crane, at Grus near Kushiro.
Lake Toya Illumination Tunnel.
https://hokkaido-labo.com/hokkaido-december-14150Mt Hakodate, Asahiyama Zoo near Asahikawa, Sapporo StellarPlace, Noboribetsu Onsen, Otaru Canal, Mt Moiwa, Rokkatei Confectionary, Odori Park, Hokkaido Shirine, Mt Hakodate Obervation Deck, Maruyama Zoo in Sapporo, Shiroi Koibito Park, Cranberry Confectionary, Mt Okura Observation Deck, Goryokaku, Hakodate, Yunokawa Onsen, Kamaei Kamaboko Shop in Otaru, Kanamori Redbrick Warehouses in Hakodate, Hachimanzaka and Motoi Slopes in Hakodate, Lake Toya, Jozankei Onsen, Noboribetsu Hell Valley, Jozankei View Hotel, Sapporo TV Tower, Nakajima Park in Sapporo, Sounkyo, Sapporo Dome, Mt Okura, Mt Hakodate Ropeway.
https://www.jalan.net/kankou/010000/?screenId=OUW1021Blue Pond and Shirahige Waterfalls are reachable by a regular bus bound for Shirogane Onsen in the daytime, or a Biei View Bus tour in the evening.
http://www.hokkaidox.com/wp-content/uploads/2017/05/2-17-BUS-TIME-TABL...https://www.biei-hokkaido.jp/en/cruise_bus/#cruise01Wakasagi fishing on the frozen lake Shinotsu was opened on 7 Jan 2017. How about this season? No reservations are needed on the weekdays. It is located 30 km away from Sapporo. JR tarin to Kamihoromui and a bus to Shin-Shinotsu Onsen is a way to go.
http://www.wakasagi-tsuri.com/hokkaidou/shinotsuko/http://www.tappunoyu.com/fishing/http://kodoberu.com/shinshinotsu/shinotsu-kouen.htmlMt Moiwa ski resort is the closet sky area from the downtown Sapporo. It is on the south side of Mt Moiwa Ropeway. There should be a bus in the season.
http://www.rinyu.co.jp/modules/pico02/Sapporo Factory is in the central downtown. About 1 km east of Sapporo Clock Tower.
https://sapporofactory.jp/
Mt Asahidake Ropeway is reachable by a regular bus from Asahikawa.
http://asahidake.hokkaido.jp/en/http://www.asahikawa-denkikidou.jp/kyouei/ideyu%20gaikokugo(2016.10.1)...Munchen/German Christmas Market is at Odori.
http://www.sapporo-christmas.com/english/Lake Toya is reachable either from Sapporo or Noboribetsu.
From Sapporo, there are some direct buses running to Lake Toya. Reservations are needed. The route is Sapporo-Jozankei-Lake Toya.
http://en.laketoya.com/access/http://donanbus.co.jp/kougai/wp-content/uploads/sites/4/2013/11/郊8-中山線.pdf
From Noboribestu, there are few direct buses running to Lake Toya. The frequency is much higher by the route of Noboribetsu Onsen - JR Noboribetsu - JR Toya - Toyako Onsen.
http://www.noboribetsu-spa.jp/?page_id=94&lang=enDirect:
http://donanbus.co.jp/citybus/wp-content/uploads/sites/5/2013/11/%E9%8...JR Noboribetsu:
http://donanbus.co.jp/kougai/wp-content/uploads/sites/4/2013/11/%E9%83...JR Toya:
http://www.laketoya.com/images/pdf/on_season.pdfSapporo Stellar Place is in JR Tower. T38 Observation Deck has also nominated as one of the top 100 night views as well as Mt Moiwa. Mt Okura and Sapporo Dome also offer a good place to enjoy night views of Sapporo.
http://www.stellarplace.nethttp://www.sapporo.travel/choose/keywords/night-view/?lang=enhttps://yakei.jp/japan/pref.php?p=1&a=2Back to your itinerary, I would go to Beer Museum in the evening. Try to go to Tanuki Koji Shopping Arcade or some markets; Nijo and Sapporo Jogai. Tanuki Koji is in the area between Odori and Susukino.
http://www.tanukikoji.or.jp/https://www.japan-guide.com/e/e2163.htmlhttps://www.japan-guide.com/e/e5317.htmlhttps://www.japan-guide.com/e/e5310.htmlOtaru is a kind of museum cities. Both Kitaichi Glass and Orger-Doh are famous. Otherwise, try Aquarium and Mt Tengu. Mt Tengu also has a ropeway and a sky resort like Mt Moiwa in Sapporo.
http://www.hokkaidox.com/wp-content/uploads/2017/05/d2d09419c053fcbd70...You may check some of the markets or a huge shopping mall in the bay area in Otaru.
http://www.asaichi.ne.jp/hokkaido/otarupage.htmlhttp://www.wingbay-otaru.co.jpHoheikyo - Jozankei - Sapporo Kokusai area is one of the best autumn foliage viewing area in Hokkaido in October. Jozankei - Sapporo Kokusai would be popular in the ski season. Hoheikyo Onsen is rated as the top day-trip onsen in Japan. I may go straight to Lake Toya, possibly stopping there in the morning.
http://www.hoheikyo.co.jp/en/You may go to Lake Shikotsu instead of Lake Toya. Or, go to Sounkyo to ride on Mt Korodake Ropeway in stead of Mt Asahidake Ropeway. If you interested in ski, there are direct buses to some major ski resorts such as Niseko, Rusutsu, and Furano. If you leave early, they would be doable in a day.
http://www.access-n.jp/winter2017/en/skibus/If you plan to go to Tokyo by train, it would be worthwhile to stop at Hakodate.
