Whenever we visit Grandad he likes to spoil us and takes us out for lunch or coffee and dd loves to order chips with aoli and a fluffy, she enjoys the whole experience as we live in a more remote area. Grandad is also a big gardener and I watched them both last week going around the garden each morning with Grandad talking about what was in the garden etc. Plus reading books is also a favourite. I don't think you need to try too hard as long as Grandad takes an interest in them thats really all they want.