I use xrced (comes with wxPython). The GUI is defined in xml files, you have an autogenerated python file that automates some initialization then you subclass those autogenerated classes and do the rest of the initialization by hand. I find that this is a good way to blend the elegance of hand-written GUI code with ease of GUI code generation.
For the code I use WingIDE, it's helpfull to have a good debuger and good source code completion when dealing with large libraries (or frameworks if you will) like wxPython.
If you want more automation (and so, uglier code) try the latest version of Boa, there are some nice introductory screencasts for it at ShowMeDo.com
