I really like Squarespace too, but just be wary if you have a site information architecture that needs to go beyond 1 level of menus. It doesn't handle sub-levels well.

I'd also really appreciate it if they let you save a template page (eg for a landing page) for easy re-use. Re-creating specific landing pages and thank you pages for each campaign we run is a bit of a pain as what I really just want to do is change a few paragraphs of text and update an image or two for these.

The lack of multiple levels of menus is something I noticed with Ghost too, when I last played with it.

Also I'm wondering, with Squarespace, it's not clear whether you can install on your own server or not

You cannot self host square space.