After downloading a number of programs, running them, installing them and hoping all would work out, I stumbled upon the answer - RapidWeaver, from Realmac Software. RapidWeaver not only accomplished everything I was looking for, but it easily integrates with Apple's iLife applications, so if I choose, I could post a photo journal, run a podcast, or manage a more global site, beyond the blog.
RapidWeaver is a stand-alone Mac OS X application, which comes standard with a variety of customizable themes, offers comments, powered by HaloScan, and has a very simple interface. It's not perfect - we're still aching for the introduction of permalinks, which they swear are coming in version 3.5 in the next few months, and it's not portable - meaning I can only update from the home laptop. As a result, you'll see a dramatic scarcity in blog entries, say between 8 a.m. and 7 p.m. every Monday through Friday.
If you run Mac OS X (and you should), and want to get started, I'd say give RapidWeaver a shot. You can download a trial here.