If you want a non-portable interface, I suggest use Win32::GUI with "The GUI Loft" for design the GUI.
Otherwise, for portable interface, I suggest Gtk2-Perl 'cause it's easy almost like Tk and it has a variety of tools for RAD development (like Glade).
WxPerl is a very valid framework too, maybe it's little too much OO, imho. WxPerl has a RAD tool too (WxGlade) but it is written in python (argh!).
Negative thing of Gtk2-perl is the necessity to install the relative libraries.