I recently ran this workout:
4x800m, 3-minute rest, 4x400m 2-minute rest
2:37, 2:36, 2:35, 2:35, 72, 73, 72, 71
The 800s took effort but felt smooth and controlled. The 400s didn't feel the greatest, but I wasn't dying.
What would be a good time for 1600/3200m?