I think you are very much on the right track, and given your description of what you want to do, I highly recommend either Joomla, or WordPress (yes, WordPress!).
1) Joomla, particularly the newish 1.5 version, is likely to provide all the functionality you need but is more "full-featured", meaning it might involve a bit more learning to use efficiently.
2) WordPress, while generally used as a blog platform, is highly usable as a basic CMS given it's "pages" functionality. I know of one web "designer" that builds everything in WordPress and ends up with projects that look nothing at all like blogs, but retain all the ease of editing and content creation that a "blog" package offers (which makes it really easy for her users!).
I think WordPress is easier for "non-techies" to get their heads around, but that Joomla is the more powerful platform overall.
Drupal is nice too, but I don't think it is as easy to use for non-technical folks as Joomla or WordPress.
You might also want to take a tour around http://opensourcecms.com, where you can see these, and many more, FOSS cms systems "in action" (you can log into as a user, , play around the admin areas, etc.) because there are many other packages out there.