Planning & building a multi-site CMS

[bcamp1973]

I'm looking to build a modest multi-site content management system. Simply put, a system that will allow me to build and deploy multiple web sites using the same DB (MySQL in this case) and same server root directory structure.  The sites will all be for one client to maintain so i don't have to worry about security issues between sites.  I've built a modest multi-site CMS in the past, but i've learned a lost since then and I'm trying to approach this one a bit more prepared. Looking for feedback from anyone that may have done such work and can make any recommendations on coding practices, point me to tutorials or other reference materials etc.  I'm still exploring prebuilt solutions like Joomla/Mambo, WordPress, TextPattern etc. However, for the most part they're not looking like a good choice for our needs.  So, for anyone that's able to contribute, i'd love to hear your thoughts!