Wordpress with Haml/Sass
You probably want to check out WORDLESS https://github.com/welaika/wordless
It's a Wordpress plug-in that comes with compass/SASS, CoffeScript, and Haml.
I'm in the same boat with respect to the sites with a low demand for customization. I'm so used to Haml and Sass that going back to HTML and CSS seems painful. PHamlP has gotten some good reviews, especially because it supports Sass: (http://code.google.com/p/phamlp/). Still, there's no substitute for the real thing.
If it were my project, I'd consider Compass and just do a compass update when I made changes. Sass is too good to pass up. Haml is your daily bread and butter, but Sass can really help you make pages sing. It suggests stylesheet refactorings you might never have thought of otherwise.
Here is a new plugin I just released: http://wordpress.org/extend/plugins/wordpress-sass/
It does use PHamlP, with all its warts, but at least it doesn't require Compass on the server.
The plugin is very simple to implement and automatically regenerates your style.css whenever the style.scss file (or whatever you choose to name it) is updated.
More info: http://blogrescue.com/2011/12/sass-for-wordpress/
Ed