A few things that would make my life much easier:
1) When selecting "Unified" anchor, put checkboxes next to Left, Right, Top, Bottom to turn them on or off. I know you can do it by using Advanced and deleting the object from the fields for the ones you don't want, but that's unintuitive and takes up a lot more inspector space.
2) There should be a way to set a fixed width in scene mode for designing your UI, and not have it automatically move around when you resize the play mode window. Nothing else in my scene view while in scene mode reacts to me moving or scaling the play mode window, so it's disruptive to have NGUI do it. Especially since I usually have the play window under the scene window, and enlarging the scene window so that I can have a better view of my GUI has the exact opposite effect because it causes everything to fly off to the sides of the screen in whatever ridiculous aspect ratio the play window is in.
3) We should be able to set the size of a non-clipping panel. Currently to make something like a window I have to make both a panel and a blank widget and set the size in the widget. This seems dumb since a panel has its own rect already and just adds more clutter to the hierarchy. I think for most people, the use case of a panel with some sort of size to it comes up much more than a use case where you need a panel of infinite size. I guess a simpler way would just be to make a panel a widget. Is there a reason that a panel is not a widget? Maybe you could add a "Window" or "Container" class that is basically just a panel-widget, if you need to preserve backwards compatibility for people who need infinite size panels?