The Drupal starter theme Zen is known for its quality code and extensive documentation. But it does require copying many files, performing global replacements, and manually setting column widths.
The Zenophile module allows one to do all that within the Drupal user interface. At Appearance > "Create Zen subtheme", specify the settings of your new theme: the machine and human names, a description, and a target directory. Optionally, you can select an alternate base theme, change the layout type from fixed to liquid, and create a fresh CSS file. Your sub-theme is then built for you. (The Zen theme need not be enabled.)
The submodule Zenophile Midnight helps in building subthemes with a light-on-dark color scheme, by inverting or darkening the colors in the standard Zen Sub-theme Starter Kit. Zenophile Sidebars provides controls in the UI to set the placement and widths of the overall page wrapper and the sidebars.