theres a ton of processing examples
http://www.arduino.cc/playground/Interfacing/Processing
but honestly I dont use processing. If you want a GUI your going to have to find one and mod it, or build one from scratch, its a visualization system, on top of java. Though if its something simple its not THAT hard
the visual systems is abit more complex as your dealing with the windows API, and its not interpreted so its not going to run on other systems, but as you mentioned you can drag n drop crap in a window, fill out the code structure and have an app
and honestly if your learning something new visual is more useful in many other areas in the grand scheme of things