Beyond the Blog–using WP for CMS

I am working on my second WP site. And I am using it strictly as a CMS.
But For this one I’m trying to make an organization plan for the pages and items and such.

It is for a group of apartments. So the site will have it’s static pages that are the contact us, about us, history.

Then it has a page for each complex. These complexes have items that i figured would be set with custom field such as: address, phone, imgs, features(like trash pickup, gym, etc.)

then each complex would also have a list of units that would have custom fields like: floorplan, imgs, amenities.

I’ve downloaded some plugins for write panels that I figured I would try for help with all the custom fields.

My big problem is with associating the units to the complex. I figure both are going to be posts. Or should the complex be a page and the units be posts? Or should I add another custom field for complex to the posts and group them together that way? then just create in the template files a filter that will only show post with that complex set in that field. Or is there a way to link them via parent and child relationship?

Any thoughts on the best way to proceed?