We're having our 10 week old GD staying overnight tonight. I had thought about going to her house, but I have such trouble sleeping, that being in a strange bed would probably keep me awake all night!
DGD is, however, very used to being in our house, as my DD stayed with us for 5 weeks, initially to recover from the C-section, but subsequently because the baby had such bad colic that DD wasn't getting any sleep and needed support.
I think what you need to consider is: how familiar is your GD with your home? If the answer is 'not very', then would you be comfortable in hers? If she is very familiar with your home, then do you mind having to cart all the 'stuff' to yours?
Whatever you decide, have a great time with your GD