I'm sorry, I saw the second post before I saw the first.
Yes, I LOVE Wordpress. I run several sites using it as a content management system. I tried several, and for me at least WP was the simplest.
I wrote the plugin because I wanted control over my own genealogy data, rather than uploading it to a site like ancestry.com. Of course, using that site, some of the features are more mature, and it gets more hits on searches.
rootsPersona displays people as pages, but you can certainly blog - thats what the front page of my site displays. I also broke down each 'panel' of the persona page into separate codes so you could include an excerpt in a post - like if you wanted to show a small tree and talk about it.
Take a look at my site to see how the pictures display (I think you've already done that based on your second post).
Separate trees - hmmm. My first recommendation would be separate 'sites', even if they are hosted from the same place. Security becomes a potential issue if you don't split it up that way. Every instance of Wordpress is a separate 'site'. You just install it into a separate directory.
I have started a forum over at ed4becky.net, if you want to post questions over there as well.