It seemed that Perl allowed me to leverage my existing knowledge of UNIX utilities, regular expressions, etc. So using it wasn't completely like learning a new programming language and a set of libraries at the same time. In other words, the startup cost wasn't all that high.
I agree with comments about doing anything too complex with data structures in Perl. I am sure there are people that easily remember the syntax for returning a reference to a hash of hashes, or whatever. I'm not one of them. Every time I have to work on applications I wrote previously that did this, it's a couple of hours of googling and trying things out in the interpreter.
If I had to write or rewrite a large application today, I'd probably use Python. I learned it fairly well about ten years ago and enjoyed working in the environment.
In my secret inner fantasy world, I'd use Common Lisp exclusively, my colleagues would just agree that it is the best programming language ever, and we'd spend our days sitting in an outside cafe in San Jose, drinking espressos, hacking our .emacs files "for efficiency," and telling stories about how we used to boot computers by first toggling in the boot loader from the front panel.