gawaHUD
Simple mod to auto-hide various parts of the user experience, allowing for a fully immersive experience. Minimal configuration to support hiding behaviors and disabling addon in instances. Also centers tooltip at mouse position.
Interfce configuration out of combat to fully hide all elements (minimap overlay is separately configurable from the base minimap), with the minimap hidden at 75% opacity. On mouse over each group of frames, they would reveal.
Example of the options panel. Should be very simple to understand and configure to your liking.