So basically my idea is this:
Custom Post Types are still Posts right? So is separating all different custom post types into their own menus necessarily the best idea? I’m not saying it isn’t, I’m just hoping to start a discussion about it. I actually see in some cases it being good, and in other cases it being bad.
For example, currently if you have three different custom post types, your menu is going to look something like:

This isn’t necessarily bad, it’s actually clear that these are different than posts, but at the same time, custom post types generally represent some type of content. So would it be better to combine that into one menu so that it would look something like:

And then when you expand the “Content” menu you would have all your different types of content listed…maybe something like this:

I had the idea, and kind of wanted to see what that might look like and edited some screen grabs to flesh out the general idea. Let me know what you think, is this better or worse than having separate Post Type menus? More importantly why is it better or worse.
UPDATE – When I was writing this I thought “surely someone else has thought about this”…did a quick G Search and saw that Nacin had worked something out about adding your CPT menus to submenus, which is good, but then I wonder if it would be better to default to CPT menu’s being submenu’s instead of top level admin menus? I still wonder if it would be better to have Posts & Pages under one “Content” menu item..and then have CPT default to showing under “Content”? Plugin/Theme authors could still override it and make their menu item be top level, but that is more work for them. Which means most of them may not put in the extra effort, where as now plugin and theme authors have to put in more work to clean up the admin interface.
Additionally adding the light blue background breaks up the submenu list and signals that these are somehow different. The light blue may not be best, since that is the same as the hover color, but you get the idea. And if everything is in the submenu without any separation then I’m not exactly sure that’s great for new users whose themes add a lot of submenus or if they enable plugins that add a bunch too. Adding to the submenu looks like:

That “CPT3″ represents a custom post type, but how does a user know this is a custom post type? I could see plugin/theme authors thinking “if I add this as a submenu item, my users won’t know that’s not something to do with a “post”, so then they opt to make a top level menu, just so their users see it easier.
Anyway, just a thought I had.