It will be our 4th visit to Lapland and we can't wait as we are getting married over there. The Immelmokit cabins are in a lovely quiet location near to K5 hotel, and we've always gone for the larger cabins over last few times as so big and worth paying the extra. Levi is great for adults and kids, with kids land etc - we love it !!!
Immelmokit cabins have everything inside you need - I'd recommend them as they are large and close enough to amenities if you don't mind a short scenic walk.
Be prepared for the extreme cold as the last time we went it was minus 35 !! - this was at the end of January but other times we've been it has been much milder.
Well worth renting out snowmobiles when you're there - great fun.
Lapland is not cheap so half board option worth considering if you like your food although last time we went with a vegan so she preferred to cook her own food using the supermarket, so worth remembering that vegetarian options may be slightly more limited than in the UK.
There are many excursions / places to visit but if you prefer to do your own thing hire out a snowmobile and just enjoy the beautiful scenery.