My parents look after DS (2) when I have to work. They take him for the full day, from 8ish until DH comes home (6pm). This happens about three times a year and the last time was last week.
Grandparents (my side) requested that rather than take him for the full day, I take him to nursery in the morning and they'd collect him after their lunch. This way they'd only have him for 4 hours rather than the usual 9-10.
I was ok with this, though DS LOVES their company and acted up a bit when I took him off to nursery. The problem really was DH, who felt that they should want to take him for a full day. As he saw it, they weren't doing anything with their free morning and they could have been having fun with DS. I see his point to some degree - GP's like to do crossword and a long leisurely breakfast in the morning and this way they could keep to their routine. DH thinks routine should go out of the window when their with us and DS, like ours does when we visit them.
He also pointed out that many of our friends have parents who care for their kids once a week or more, we only rely on them 3-4 times per year and it's a bit of quality time without us around.
Who's being unreasonable? My parents are early 60's and very fit and healthy.