You get what you look for. Look for a particle and you see a particle. Look for a wave and you see a wave. The point is that both wave-like and particle-like behaviour exist simultaneously up to the point of observation, at which time the probability wave collapses into either one or the other.
This is the basis of the uncertainty principal. You know - the cat that's both dead and alive until you open the box and take a peek. Its a true and very interesting fact that the interference pattern you mention can still form even when single particles are fired at the slits, but the experiment is set up to look for wavelike behaviour and so finds it.
The cloud chamber experiment would be only be able to show particle interractions, so any results would just be confirming particles.
