Laravel (http://laravel.com/) if you want to pick up best practices (yes, there are best practices in PHP) and mess around with MVC and such, or Slim Framework (http://www.slimframework.com/) if you want little more than the bare essentials. In both cases, I would recommend using Twig for templates. None of this is particularly controversial, though, but in my opinion the only faster way to get a site up is wordpress, but on the programming side, that's a lot messier to work with.
Of course, the people who will recommend Ruby and Python and whatnot are right too - you can get a reasonable set of frameworks and deployment strategies in various languages. But the case for PHP is, essentially, lack of overhead and low cost deployment. If you can stand an ugly looking weakly typed ad-hoc language, that is.
Ruby on Rails is sexy as hell, Node + Javascript is very nice, but for practical, workmanlike, somewhat-ugly-but-does-the-job prototyping, PHP is the way to go, IMO.
It has the additional, significant advantage that there are far, far more tutorials and general Google answers for PHP than any other language - certainly than newer approaches like Node.
You'd get to learn just one language this way. Besides, JavaScript has a relatively easy learning curve.
There's a ton of tools and frameworks and very large userbase. So you can get help.
Or you could use Delphi...
You can export from Balsamiq to HTML. See "Exporting your Mockups to Code" - http://support.balsamiq.com/customer/portal/articles/135659-...
1) rails + Heroku. Rails for the community and plethora of pre-built wheels, and Heroku for the absolute brain dead deployment of your creations. (you'll need to learn like 4 git commands)
2) I'll prototype your ideas in any language you want if you give me access to your network. Deal?