Definitely look at PyQt. It was the GUI framework I chose when going
through the same process 3 weeks ago. I have to disagree with F.Geiger
(sorry, F.Geiger), I think a GUI builder is a necessity. It saves you a
lot of time. The alternative is to keep changing your code until your
GUI looks as you want. With a GUI builder you "draw" what you want and
have the tool generate the Python class for the GUI. It also sets up
event handlers for you too.
Visual elements are best designed visually!!!