This aspect of software development was largely missing from my formal educational experience in programming language paradigms.
What I am trying to do now is develop a better "taste" for what is "easy" using one programming paradigm compared to another. I'd ultimately like to have a better problem to paradigm mapping internalized. I've toyed with the idea of putting together a seminar or undergrad course to do flesh this out.
The elephant in the room is more market based - what programming languages will someone pay you to use in the future? We already have a number of interesting programming languages. But when you do your job search these days, I see a small number of large buckets. The .Net/CLR C# world, Java in the enterprise, Ruby (really the Rails framework, but even so), and a strong side of the data storage backend of your choice (RDBMs or NoSQL or sexps - kidding on that, pg keeps our own forum in files full of sexps).