This is very interesting. I don't know if you are aware, but I've followed a similar (although not so sophisticated) approach with the UMazel Starter Kit (in fact, I followed part of uSkinned's approach on their themes).

Specifically, I'm using nodes without templates, grouped under a parent node and rendered on the first "page" ancestor level. I included a node reuse concept by adding a "Reusable Content" node and a picker to select things from it to use in other pages, using a special type of "placeholder" node.

(Disclaimer: I'm not advertising myself - not much, anyway :) - I just thought that my own site would be the best example since it's based on the UMazel Starter Kit and follows that approach. I've followed this approach on dozens of sites I've developed, but unfortunately I'm not allowed to show here).

Here you can see how this is depicted in the Umbraco back-end. The circled nodes are "content sections" grouped under "Page Elements" (a node that is automatically added under every page node via the AutoNode plugin) and they are all rendered as part of the "Umbraco Services" page. You can see the end result here.

For reusable content, there's this node that stores sections that can be reused. This means that if you change the node's data once here, they'll be changed everywhere it's used.

To include reusable content in a page, I've got a special "placeholder" node which features a picker to choose items from the "Reusable Nodes" folder:

All nodes are rendered via a "SectionRenderer" partial view that chooses the correct partial view for each section (based on conventions) and takes care of caching using keys so that it caches sections individually even when there are multiple sections of the same doctype on one single page.

A different tree would be a good idea. I think that my approach resembles what you described a bit - although it can take some improvements, of course.

Would it be a good idea to have the whole thing made reusable in some manner?

Yes, that would be sort of the current way to go about it. But I think that the separation of blocks from pages works really well.

I think it would especially make sense with the upcoming localization features that seem to be coming in V8. That way you could make a block that could be used across multiple languages/sites.

The concept of a "Set of blocks" is nice. I'm not sure if that actually exists in EPiServer. But I guess it would be sort of a "Block area configuration" or something. It would make it a bit harder to do stuff like validation of which kinds of blocks are allowed to go in an "Area".

If we take a page from the Sitecore playbook, they have the concept of a "Rendering", where you can basically insert a piece of content, with a configuration on top. So you could for example say: Add this "Newsletter signup" block here, but use a different theme or list or something.

Could you point me towards any info on v8's localization features? I looked at the roadmap, but I didn't see anything about localization.

With fear of sounding like a broken record. Totally in for what Jason is saying. Would be really awesome to somehow get the possibility to "divide" the nodes in the tree, something like:

Site

= > Contentpages

-- some kind of breakline --

WorkItems (maybe a kind of folder)

ie => FrontpageSliderImages

-- some kind of breakline --

System (only to be seen as developer)

ie=> Accountpage, Loginpage, Access Denied and so on.