recommend a framework/library that "is here to stay" and have a "hire-able" value?
You are asking people to foretell the future. How can we know what may be in vogue next month or next year, or what experience employers will be looking for? My best advice would be to get away from C++ and look at WPF, HTML 5 etc; but then, what do I know?
One of these days I'm going to think of a really clever signature.