Great thread.
I like to do workouts of two or three broken 800s, as 2-3x sets like...
200,200,400
200,300,300
300,500
200,600
Usually with 2:00 interval recovery, 5:00 set recovery. Better developed runners can probably take 90 or even just 60 seconds.
The 200,600 especially is damn near a simulation of the bad place a quality 800 takes you to.
Closer to a race I really like the 600,200 mentioned above, or something like 4-6x200 at a bit faster than race pace. In the last 7-10 days before a peak race, you want to feel GOOD at race pace; suffering is for the weeks before.
Good luck!