PHP is fine, but if you want to learn about a better, enterprise-ready languages I would suggest using ASP.NET. It integrates perfectly with
.NET apps and libraries and comes with a comprehensive library (as it uses
.NET). The great thing about ASP.NET is that you can use C# to develop for it. ASP.NET also comes with various functions to make state management easier - an important feature that is completely missing in other languages. It also has built-in cache management.
ASP.NET originally lacked templating engine, but Microsoft introduced it in 2.0 version. You can have master templates that have placeholders for the dynamic content, as well as all the HTML and JavaScript that is shared between all pages.
It is basically
more than your off-the-shelf PHP/Python/Ruby. ASP.NET provides much larger library to use, has templating engine, error handling, controls and events (and hence is more familiar to Windows developers), caching, object-oriented design and session control which can even be saved in SQL Server. It's not just a language, it's the complete package.
One of the great things about ASP.NET is also that you can use your favorite language to develop for it, as long as it supports
.NET. This means you can use VB.NET, C#, J#, Delphi.NET etc. And because you compile the code to bytecode, it runs significantly faster. On top of that Visual Studio is a great free (and commercial) development environment.
Oh, and if you want to run ASP.NET under Linux servers, it's easy too. Apache has
mod_mono module or you can use it via FastCGI.