I have a toddler and a teen.
Teen is an avid reader (and toddler is beginning to be, too), so lots of trips to the library and lots of reading time.
Both are helping with renovation- and home-improvement work; while the toddler is learning how to use a screwdriver and hammer a few nails into place (all fully risk-assessed and supervised, of course), the teen is helping paint walls.
Both are involved in keeping our garden in shape, from pulling weeds and watering to planting a few more bits, re-proofing furniture and taking care of what little wildlife there is.
We go on walks and have picnics (which both children help me prepare).
The toddler may learn to use a bike this summer, or continue with the balancing bike for a while.
Both will be doing some arts and crafts, from painting to (in the teen's case) using old (and stained, so not fit for charity shops) clothing to practise sewing.
We will bake, sort out everyone's rooms, recycle old school stuff, which is no longer needed.
The toddler enjoys helping me with laundry.
Both will join relatives at the seaside for a while, so will also go swimming, paddling, crabbing.
Regular visits to the park while the teen is off to see friends.
We will also go on holiday for a bit at some point, for which both will practise the basics in language - just saying hello, please, thank you, numbers and maybe a few food items.
One has their birthday during the holidays, so we have a day out planned then.
But, for the most part, we won't be spending much money. Children don't need constant expensive entertainment; there is always plenty to do.