SquareSpace seems to be the big leader in the easy-enough-for-mom website space. To compete, I think you need to really differentiate on features and also somehow indicate you plan to be around for the long term.

The reason this is important is that long term sustainability is probably the most important feature for websites for non-nerds. People just don't want to deal with moving content to a new service, learning a new interface, etc. For this reason I would only recommend something that looks like it will be around for 5+ years. I'm confident that SquareSpace is stable and has a business model that works, whatever other flaws they have.