I'd like to have a setup along the lines of a trio of 5x5 disc-corkscrew traps before a line of 5 or so 10x spike traps with a pressure plate between each of them setup as so:
P1P234P5PP -- 10x Spike Trap arrangement
1 4 2 53 -- Pressure Plate assignments
That way, the invaders (especially if there's a ton of them all at once) continually screw each other over with the spike strip, provided they bypassed or jammed the spinner trio at the beginning; and even an attempt at escape, considering the delays between pressure plate usage, should still get them on the return out if they panic, and if they somehow bypassed that (either by being too fast or too slow), then if the spinner trio unjammed themselves in time, it's one more pass through that.
Of course, even if they don't panic, another spinner trio will be waiting for them at the exit with maybe a cage trap for the lucky SOB that's now my prisoner. A drop pit of varying depth under a drawbridge remains between them and the entrance to my fort. Provided they survive the fall, they may or may not be let out of the pit, or mercy-killed by a trainee.
EDIT:
Of course, naturally, all pressure plates will be assigned not to trigger by my residents. Don't want to have ‼fun‼ that way yet. Could work for danger rooms, however if you assign a squad into one.