LyX is halfway there. It is a visual editor for LaTeX, but it does not actually show the final result. Instead, it operates on an intermediate representation. Stuff like section headings, math environments and tables are shown correctly (unless you use non-standard features), but margins and spacings are not. Ergo it isn't suitable for designing, or nitpicky typography. It calls this approach WYSIWYM – what you see is what you mean.

The user experience is quite similar to your regular word processor, except that the “paper” metapher is removed.

I tried it out for a while, but I feel more productive (and more in control) when using a regular editor with nice syntax highlighting.