I would go with something router based. The majority of the above average home routers do allow you to configure either your own list of allowable and/or blocked websites, or use a subscription service that will maintain such a list for you.
My D-Link gamer router does just that - I can set up my own list of allowable websites and configure times where access to all internet is blocked. It can be applied to specific computers on my network, exempting others. Also, you can choose to log what websites are accessed from the computers on the network and have the logs emailed to you from the router.
The router also gives 30 day free trial access to Sentinel services for real-time list updating of adult, offensive and hate sites. As I don't use it, I'm not familiar with the subscription costs.
But as I said, I would go with the router solution. I say this because it's far simpler to maintain the setup from one device, with one subscription, than to do this on multiple machines.