The fact that Custom Post Types can't be mixed in with Pages in a site's structure is a real problem for some use cases. I've searched and experimented, but haven't found a solution - including looking at using Custom Taxonomies in conjunction with Custom Post Types. If someone's got a suggestion, or I've just overlooked an obvious solution, I'm all ears.
Problem #1: Posts of a specific Custom Post Type must be arranged under that Post Type's slug
Problem #2: Pages can't be nested under a Custom Post
Problem #3: Custom Posts can't be nested hierarchically
Custom Post Types have been touted as the feature that turns WordPress into a "real" CMS, so I'm going to provide a real-life business scenario here that shows the limitations of the current Custom Post Types restrictions.
- EXAMPLE Travel offers travel packages for multiple resorts in each of multiple destinations (e.g. Bahamas, Bermuda).
- EXAMPLE needs to record and display structured information about each resort and each destination - so they've decided to create two Custom Post Types - "Resort" & "Destination" to handle this.
- EXAMPLE wants to organize its Resorts by Destination, both in menus and in the permalink structure e.g. example.com/bahamas/royal-palm-resort/, example.com/bermuda/elbow-beach-resort/.
- EXAMPLE would like to show a list of Resort "teasers" on each Destination page (so, example.com/bahamas/ would automatically show a list of teasers, one for each Bahamas Resort, based on information in each Resort's Custom Post)
- EXAMPLE would like to have Destination subpages (standard Pages) that contain details like safety considerations, customs information (e.g. example.com/bahamas/safety/ & example.com/bahamas/customs/).
- Similarly, EXAMPLE would like to have Resort subpages (standard Pages) showing details about each resort (e.g. example.com/bahamas/royal-palm-resort/golf-course/ & example.com/bermuda/elbow-beach-resort/scuba-diving/)
- EXAMPLE wants to have a standard blog at example.com/blog/ and standard nested pages (e.g. example.com/about/ & example.com/awards/2010-excellence-in-travel/) in addition to the hierarchically-organized Destinations and Resorts.
Correct me if I'm wrong, but this doesn't seem to be possible (or at least it's not obvious how to set this up) in WP 3.04, at least without jumping through some major hoops.
I was excited about Custom Post Types as a way to save more structured, searchable information than normal Posts and Pages allow you to easily do, but most of the examples I've seen online are very shallow - a flat collection of books or a catalog of movies. If you want to do anything more complex, it seems you're still out of luck.