And when you right-click a window and select "Window Settings", you can change the opacity (fade) of the window. You can turn them down to become invisible unless you mouse-over them.
This allows you to see the viewing screen without having lots of clutter.
I have 4 hotbars and 3 chat windows. All but 2 hotbars are invisible unless I mouse-over them.
I tend to always run 2 bars - each 6 buttons long and 2 buttons high. When I craft, I add a third set dialed over to whichever set of crafting buffs I need at the moment. This third bar gets dragged up underneath the main crafting window so I can get to all the buttons without having to move the mouse all over the screen.