I recently put a commercial template on a clients site but found the font size too large in the main menu so adjusted the css to give a better look. This mod caused a problem with sub-menus that the menu designers couldn't suggest a fixed after numerous emails and 2 weeks of time.
I gave up and reproduced the look of the template in Artisteer in a short time (less than tweaking the original CSS).
In Artisteer you still need to tweak the css to get the look you want but once you know how it works it's not hard.
This is my main site (still evolving) made with Artisteer -
yws.com.au.
For a fix width template without the bells and whistles - Artisteer is a good investment.