Google Analytics has a Demo Account that uses Google's Merchandise store for sample data purposes:
I wonder if this is only in-Google Analytics data though, you may have to check.
Thanks Matt. I was able to access Demo account and it looks like it's only accessible within Google Analytics. I was also able to successfully create a connection between Tableau and Demo Google Analytics account. But it doesn't populate the data after i select the dimensions and measures. Thanks for your help though Matthew Risley
I don't think any website would be willing to give their GA data to a third party, it could always be used for the wrong reason.
It's pretty easy to setup your own website and install GA though, even if you have a personal blog you can put GA on there.