I've used many GUI designers over the years (for different languages): Delphi, Visual Studio, JBuilder, Netbeans.
The quality of code they produce and the volume is important. Delphi was fantastic, it produced small amounts of code relative to the form size and the code was easily understandable and the two-way tools allowed you to change generated code with confidence. This was helped by a simply understood GUI library. VS produces reams of code and you do get scared to change it.
Java is partly let down by the language, no delegates or closures and so event based code can quickly become a sprawl.
I would knock up simple stuff with Netbeans Matisse and - once confident - hand code them. The complex stuff is worth planning out and hand coding so that you get your model defined well.
It helps if you build a library of your own GUI components that you can re-use. This is relevant to all languages with GUI libs.
