DS can get riled up with his paternal grandfather because he will get on the floor and play with DS. My MIL watches DS during the work week and she constantly tells us how good he is for her. Mind you he is almost 1.5 and not a bid kid yet. I have no issues with his grandparent's disciplining him which means a tap on the hand if necessary or a stern no but no screaming and no spanking(I'm ok with a light tap on his diapered butt) when warranted and necessary. Considering the approximate 40 hours per week my MIL takes care of my son, he has to listen to her and FIL when he arrives home from work or it would be complete chaos and I'm sure we would be ask to put DS in daycare.
My kids are pretty high energy, but my parents have been around them from day 1 (lived no more than 30 min from us up until recently), so the kids don't get so crazy when they are around them. They haven't done a sleep over in a year, (tomorrow night!!!), and haven't been there often without us, but I allow my parents to take charge when we are there. My parents have mostly the same rules that we do, I allow a bit more crazy, but the kids know, Meme & Papa's house, their rules. That's not to say I'm hands off, but I let my mom rule her house. They know that if they get them crazy, I will not help calm them down unless they have tried everything. My mom's good about a balance of play with them, and always finds a moment for each kid to make them feel special when they are there, even if there is a lot going on.
My ILs on the other hand..my kids don't listen to them and really just ignore them. They've never done an overnight and haven't been at their house in 6 months, and won't be for a long time. They have them at our house for a few hours here and there, but they don't really interact with them much, just watch them play or watch TV. They get excited to have the ILs around, but I think they pick up on a lot of the tension we have with them, even if it isn't said. They don't seem to look at them the same way that they look at mine.