>>Would love to hear strategies for building very high end sites.
Very high end sites is too vague a question.
Most of these so called high end sites are just Flash adverts. No really. What many people see as high end sites is just fancy flash, with very little SEO. These sites also do not change much, so less value in a CMS.
These are the sort of sites that you get paid big bucks for. You are really being paid for your graphic design skills. Plus, you only get the gig if you can sell well, or have a shoe-in from a contact on the inside.
A bit further down the line, are the bread and butter sites. The three CMS systems you highlight will allow you to build pretty much anything you want. WP does (contrary to many opinions) work well as a CMS. Joomla is really ugly and clunky, but works too. Drupal is a beast, but is far more extendable than either WP or Joomla.
There is no right answer to "What CMS should I use". Each will invariably have tradeoffs. Unfortunately, you have to learn *all* three to know which one to recommend. In many cases, all three are overkill, and you only need a micro CMS like Pixie (
http://getpixie.co.uk)
WP is great. With plugins, you can extend it and build a website for 90% of businesses out there. If you are clever about designing the theme, and widget areas, you can also make it easy for users to customise. Throw in the custom menu plugins, and you can have a pretty decent WP based CMS installation.
Joomla - I think it got lost in the great plugin war. Everyone wants to charge for their half baked plugins. Plus, it is more difficult to learn than WP, and does seem fairly set in its ways. It can be difficult to get new users to understand how it works. My biggest problem is that Joomla finds itself in a situation where it is far more difficult for total newbies than WP, but also far more difficult to truly extend than Drupal for seasoned pros.
Drupal - Quite the beast. A lot of learning to set it up just right. One of the reasons it is difficult to find themes for Drupal, is that the themes are tightly linked to the way a specific site is set up, via CCK & Views. As a result, they are not easily shared across installations. You do run into the same problems once you start using WP as CMS instead of a blog.
My take on the situ::
Learn WP. Learn it very well ... you can cover a lot in a weekend if you focus. Have a cursory glance at Joomla. Learn Drupal when you are ready to work in a team for clients paying you really big $$.