I have a good amount of experience with C# and Java at the moment but after education and whatnot I wish to be able in more than just 2 high-level, comparatively limited languages, and from what I've seen languages like C(++) or PHP are in demand at the moment. I've thought about learning the following:

• C. Very standard, lightweight and available on everything. However very old and mostly procedural.
• C++. Standard like C but I've read in some places that it encourages bad programming design and use of dodgy libraries - but similar things have been said about C too so I'll take that with a grain of salt.
• D. Quite new but looks promising, but will it be relevant or applicable in the future though?
• PHP. With the internet becoming ever more important I think this might be the one to go with, but the code itself isn't very intuitive.
• CoffeeScript (or plain JavaScript). With Microsoft's new idea of HTML5+JS for everything under the sun this doesn't look like a bad choice. However things do change and I wish to be primarily a software dev, not web dev.

So out of the above list, or any others that you could suggest, what would you say I should begin to focus on? What is your opinion on staying with C#?