Gnome classic is really pretty easy to tailor, to an extent, once you
find out that ALT+rightClick is the key. But it seems to have some
issues with focus, like new windows coming up behind other windows. And
the separation between workspaces seems not so complete as one might wish.
I haven't gotten nearly as far with fluxbox, partly because
gnome-classic is "almost good enough". Fluxbox doesn't seem to have the
problems with focus that gnome-classic has, and (as I recall) its
separation by workspace is more absolute. But I really don't like
having to right-click the mouse to pop the menu, and I haven't yet
explored the tailoring aspects.