FIL lives nearby and despite having a very busy retirement which includes volunteer work, he helps us out enormously. Up until recently (when I started mat leave) he would look after DD a day per week so we could reduce the amount of time she was in formal care. Now the two of them are incredibly close. He does help out occasionally with overnight stays (few times per year) but we don't like to ask as he already does so much and isn't getting any younger.
MIL is unwell so we don't ask her.
My parents are both a couple of hours drive away, Dad still works long hours and Mum has several mobility issues (plus she does lots with her other grand kids) so we don't like to ask her for much either. But she loves to help out of she can.
I'm reading with interest some of the comments along the lines of "they never offer to do anything". Ours generally don't offer either but we don't expect them to. If we get stuck we ask outright, we don't wait for an offer of help. It's not their responsibility?