toodeep wrote:
How do I simultaneously tile windows from different apps without minimising others first, e.g. I want to fill the screen with one of several open Excel windows and one of several open Preview windows tiled side by side?
Press and hold the green button, and choose Full Screen->Left of Screen.
The current window will tile to the left of the screen and all available windows will be displayed on the right for you to choose.

Note: just like when you put an application in full screen, these two half screen windows will get their own Space. Other windows are NOT minimized, they just remain in their Space, and you can go there using for example control-left or control-right.