While WordPress is a hugely popular blogging platform, it is entirely possible to use it in order to create small business websites. Those who do not know or care to learn HTML, but who still want to go beyond basic text editing, can use WordPress.com in conjunction with Windows Live Writer to create multicolumn tables, galleries, etc.
If you do decide to go this way, I’ve written a brief WordPress guide for my students in PBA333 that you might find useful. The original Greek version can be found as: Οδηγός WordPress.com. The English version translated by by Manolis Diakourakis (thanks so much Manolis!) can be found in WordPress.com guide.
Here’s also some free advice: less is more, don’t try to go way beyond the typography and overall format that the theme designer is providing – these people are professionals and their livelihood depends on having a good taste.
Joomla may be more focused towards ecommerce, with it’s product categories and shopping cart infrastructure, and Squarespace.com can build some solid landing pages, but WordPress is definitely an option to consider.