The reply from Diane B was right on target. I'd also note that in the whole scheme of things, a week visit isn't that long and you are right there with your daughter experiencing this trip and new adventure and her new grandparents together. Help her bond with them too and it'll benefit you all not only now but also in the future.
When I visited my parents in FL with a 4 month old, I would nurse my baby in our bedroom for naps and I'd take a book in and read while she nursed then fell asleep. Sometimes I kept her in my lap for the whole nap which I never really did at home. I guess I was figuring out some alone time with my daughter just like you are now.
If my parents offered advice or did something with my daughter that wasn't my way of parenting, I'd try to lightheartedly say, "Oh Mom, that's not my style." Or I'd simply say something generic like "That's interesting, I hadn't thought about it like that." But be sure to give your parents positive feedback and thank yous for all they do that's helpful. It's likely they are just trying to find their way through this too and want to make you and your baby happy.