the UV editor shows the UVs for the currently selected object. If you select a differnt object or nothing at all, then you won't see the UVs. also make sure an object is selected and not a face or something. Once you have laid out your UVs, you have to save the scene (or object) to keep them. I know what you mean about the UV editor though, I find the interface quite annoying - nowhere near as good as the rest of Maya.