Hi Ian Cowan. Putting my consultant "solution creator" hat on for a moment. One thought might be to create a group-connected site, and make it open "Public" to your intranet - you can add whomever to help you be owner member, and for the site itself, ensure you use one of the broader auth types, like "Everyone except external users" as a 'user' of the site and set it as a "Site viewer" - that way, everyone can visit your site, and a few can actually edit. You do all this from the upper right gear icone when you're in the site, and then select Site permissions; this will open the Site permissions pane on the right and you can then click "Share" and add the groups/people you wish ands assign the levels: Owner, Member, Viewer as you require.
Once you have that established, you can then create the home page as you like, with the components you like - and as much are turned on in your tenant, with the ability to quickly update when new components arrive (like section layouts and the Hero and People web parts). And then for your comms to draw people in, it's just a link you send in email, post to Yammer, and ensure you create news articles that highlight the things you most want to emphasize about the site - the news articles will then reach users on their personal news aggregation within the SharePoint home in Office 365 (where you land when you click the "SharePoint" tile within the Office 365 app launcher) and the SharePoint mobile apps (the news tab); encourage folks to install and update often (iOS: http://aka.ms/spappios, Android: http://aka.ms/spappandroid, Windows Mobile: http://aka.ms/spa--windows).
Cheers,
Mark