I use 4 monitors in a T shape, with all monitors pretty much angled perpendicular to my head. It's awesome, and I'd never go back!
I have the AC parent window stretched across the top three screens, with (generally) 3D window on left, floor plan+details on middle, sections+layouts on right... and all sorts of palettes open on the lower monitor, including Project Map+Organizer(Views+Layouts) constantly open.
However, it's so frustrating that AC is not multi-monitor aware and hence doesn't remember my layout of all these windows when opening a project. Only some palettes appear in their remembered place.