My company builds websites for membership-based associations. We currently use custom DLL's (written in CodeGear Delphi) which interact with a SQL Server database and use a custom HTML-based template language. Basically we build templates in HTML / CSS / Javscript with the dynamic parts being generated by tags in the format <#TAG NAME>.
I've been building all the templates for our clients using Dreamweaver, but my boss wants me to create a web tool which our clients can use to visually build templates themselves in our format, without needing to do actual HTML coding. For example, they would go to our site and say "create profile update form" which would generate an HTML skeleton, then they could select functions such as "add form field" to generate the correct HTML for that field based on the options they enter. The template would then be saved to the web server as an HTML file (or to the database as a blob) and used by the DLL's to generate pages on the site. They should also be able to re-visit the existing templates to edit them, and manually edit the HTML if necessary for advanced customization.
Obviously there are a lot of ways to go about this. I'd like suggestions on a server-side language (and hopefully associated libraries / modules) which is capable of building and parsing HTML documents and writing these to the file system. The tool needs to be IIS compatible, and preferably in a C-style syntax. I'm very proficient in Javascript and Perl, slightly less so in C++ and Java, and have no experience with PHP, Ruby, or Python (though I'm willing to put in the time to learn if they are the best tool for the job!).
Thanks for your suggestions!