I'm not a grandma yet but am grandma age, with a grown up married son (hope emoticon).
If I had grandchildren of 4 and 6, they would likely have stayed up later than at home, so would hopefully have slept beyond 5.30am or 6.30am.
I watch TV in bed first thing, so they'd be in with me, snuggled up, watching the children's stuff I'd added to Sky. I'd have tea, they'd have milk. After about an hour we'd get washed and dressed and go downstairs for breakfast. The big one could read to me and I'd read to the little one. I'd take them to 10 o'clock Mass and they could go to Sunday school while I had a little rest, then they'd have a raucous hour with the other children playing in the garden.
Home for lunch and I'd take them to a children's farm for the afternoon and let them exhaust themselves on the ride ons and trampolines.
During the week we'd do a beach day, the South Ken Museums, probably Legoland or Chessington, children's theatre/film, quite a few teas out - knackered grandma and there'd be lots of playing in the garden.
Repayment to grandparents doing a whole week of childcare is that they have free rein to treat and spoil.