As your grandchildren are only 5 and 8, an obvious step is to call them from whatever they are doing when you need the table or feel that outdoor toys should be put away, and ask them to help you tidy up.
This is how school teachers and nursery school staff teach children to tidy up.
If they say they don't want to, smile and say, "I don't either, but it has to be done now."
And do tell your children and their spouses that you love seeing them, but you are too old to do all the work yourself, so you need them to help tidying up kitchen, dining-room, sitting-room and bathroom. If their bedrooms are a tip at bedtime that is their affair, not yours, as you presumably don't sleep in the same room as any of them.
On the day the leave, ask the grown-ups to strip the beds and put towels they have used in the dirty-clothes basket as well.
However much you love them, it is your house, so your rules,
If they can't accept and respect this, stop having them to stay - go and stay with them and sit on your backside doing nought (except knitting ) while you are there.
I bet your grandma didn't run round doing all the work when you and your parents visited her!