BBEdit has pretty much done this for me. Lots of settings, but turn off all toolbars, etc, set a font & size for all documents, and it's pretty much equivalent (menubar still visible) except that all that power is there when you need it (if you do).

I only wish it had settings sets so I could have a "coding" setup, a "writing" setup, and so on.

Actually, it might! But there are so many settings I haven't found it yet :-P ( yah, I'm giving you one there :)).