I used to do an alternative version of paper chains - put the strips into a shoebox with tape/stapler (depending on her age each year) and let DD do them in her own time over a few weeks. It was great for filling a few minutes getting in from creche/work while I got dinner sorted, we would do it together sometimes and she would work away on her own at others. It could go back into the shoebox for safety once finished any day (chain didn't get crushed sitting on the table) and in a couple of weeks there was a long enough chain for the hall ceiling and often for her room as well.
I also like collecting pine cones on winter woodland walks (and nice sticks for the fire), and then painting them as decorations (or using them as firestarters) another day.
Free printable activity sheets from the web for DCs. It starts with basic colouring sheets, but there are great resources on loads of different seasonal themes for writing practise, word searches and quizzes, word mining, story starters, maths, geography, ....as well as lots of different ideas for crafts etc. Homeschool sites are particularly good to get you going. And often if they are fun things, DCs don't see them as "school stuff". (I used to do word mining with DD in bed as a way to focus her brain on 1 thing and stop everything else whirring, so she could get so sleep, and she loved them).
A Christmas disco in the kitchen or a floor picnic while watching a movie on tv are also great to do because they are fun and unusual activities in our house. Or DD coming home from school to find that the dolls and teddies were all having a picnic on her floor, or listening to "Big Bear" reading a Christmas story to them....or once, a naughty pair of dolls had a snowball fight with cotton balls...
DD has no siblings, but she does have a few DCousins etc to buy for. And she also buys something that she would like, as a present for someone who doesn't get many presents, and we wrap that and leave it at a local collection marked for the relevant age. I used to always take a half day from work to bring her shopping - which was only buying the things she needed to buy for others (or giving me a few ideas as we looked), getting a hot choc and bun while people watching, and visiting the "Live Crib" at the Lord Mayor's House - I left my own shopping to another time.
If you buy cloves in a big bag from an oriental supermarket or similar, they are much cheaper than the regular supermarket. Then you can have lots of fun poking holes in oranges and stuffing them with the cloves. And also get some cinnamon sticks and any other spices for hot drinks over Christmas, like cinnamon spiced hot apple juice or mulled wine (I use cloves, peppercorns, cardamons, star anise and cinnamon in my mulling spices mix). You could also make up little packs of spices and package prettily as gifts, on their own or hanging from a bottle of wine.
I also do a bath bomb - but as a wind down on the way to bed on Christmas Eve. We have a box that has come out every year since DD turned 1 with her plastic Santa plate and glass (they were a cheap second plastic crockery set which we used all the time until she was using regular crockery - we threw out the flowery one but keep the Santa one with the decorations to come out for the Christmas season), her stocking, the family copy of "Twas the night before Christmas", a new pair of winter PJs for everyone in the house, and festive bath bombs for her and I (and sometimes a nice festive shower gel for DH). We have dinner, light the Christmas candle and then bring out the box so DD can lay out her stocking and use the plate/glass to put out a snack for Santa, then runs up for the bath, into new cosy PJs, has a hot choc drink (common at bedtime anyway) and gets the story read in bed all nice and quiet and ready for sleep.