It looks like WordPress is going to be my platform of choice for a while. The decision to merge WordPress proper and WordPress Mu in WordPress 3.0, along with the buddypress plugins, makes it easier to standardized the sites I work with on a single platform. Spirit Post and andrejcarter.com have been on WordPress for a while. I experimented with Joomla for andrejcarter.com, but it was more than I needed. WordPress has always been the perfect choice for Spirit Post, and the new features in WordPress 3.0 with buddypress will enable some new functionality in Spirit Post, making it more of a community.
The KentuckyCheerleading.org site was initially on WordPress, but it was switched to Joomla because Joomla was more powerful than WordPress. Ironically it will be switched back to WordPress because WordPress is simpler. Joomla is a wonderful platform, which I would use if I needed something more powerful than WordPress, but WordPress’s simplicity is winning for now.