Sorry for being a Johnny-Come-Lately to this thread, but I just found it.
I do not like using a Hot Corner (alone) because it is too easy to inadvertently sleep the screen by random movement of the the cursor. However, there is a solution....
You can add a "modifier key" (e.g., the "Command" key) to the hot corner sequence so that moving the cursor to the chosen hot corner does NOT sleep the screen unless you also push and hold the modifier key.
To add a modifier key, open "System Preferences", go to "Desktop & Screen Saver", choose the "Screen Saver" tab, and click on "Hot Corners…". Open the dropdown for the corner you prefer. Before clicking "Put Display to Sleep" hold down the Command key (or another modifier key*) and then click "Put Display to Sleep".
Voilà! Now the display will sleep only if you hold down the Command key before moving the cursor to the chosen Hot Corner.
*I believe the only modifier keys available for this are Shift, Control, Option and Command -- you can use any one of them or combinations.