Best addon-light UI setup for casual play?

I want useful information without rebuilding the whole screen. What are the few pieces you would keep if you had to stay close to the default UI?

Default raid frames, better nameplates, OmniCD if you group, and a small aura package for your core rotation. Start there.

The built-in editor is good enough now that most players should begin with layout and keybind discipline before adding complexity.