Rather than elf on a shelf, I occasionally rearranged the teddies and dolls to have a tea party, biggest bear reading a Christmas story to them all, cotton ball snowfight going on...basically using things we already had and not needing to move things daily.
I also usually print a bunch of free seasonal colouring sheets, and as dd got older, seasonal themed maths and word puzzles etc. Some days I would put one of these with her Advent calendar choc (we have a fabric one with pockets and I get nets of choc shapes from M&S or Aldi by the start of December). Some other days, I might put a note about something we were doing later that day (visiting Santa, Christmas shopping day, baking cookies, decorating cookies, making cards, tidying room for Santa etc.).
And every December, I took a half day from work and got her straight from school (instead of after school club) to go to town. To do any bits of shopping she wants, get a hot chocolate and bun to enjoy while people watching, and see the Live Crib outside the Lord Mayor's house, before getting the bus home once it was dark and the lights were all on.
And we'd also figure out where the best decorated houses were locally to do a drive after dinner one night in the dark with a travel mug of hot choc.
and various crafts - making cards, decorations, painting Pune cones we'd collect on winter walks...I always gave her a shoebox of different coloured strips of paper already cut, roll of sellotape and kid-friendly scissors that she could make her own paper chains when she wanted to spend 5-30 minutes on it after school, put them away safe in the box to keep going the next time, and then hang when we were decorating the house.