Keep in mind, effect lights should be used for exactly that...effect. That means used for brief periods such as say a guitar solo or such. With 12 par-58's cranking these will easily wash out all but the heartiest of discharge lamp equipped effect lights.
That said, you can easily add significant "WOW" factor by simply adding a couple of Pro-Gressors linked in sound active mode and cut the par cans and hit the effect lights during the songs breakdown/guitar solo etc. and light the whole joint up! Keeping their use to a minimum of say 30seconds or so keeps the "WOW" factor way up there too.
At the end of the break, simply switch from the effects back to the Par-58's.
Another very simple, yet extremely effective effect for bands especially is this: A 2' section of pipe with 4 pinspots splayed (spread your four fingers out and you get the idea of what I mean by splayed)on each 2' section. Use 4 sections of these four pins, one on each side of the stage either mounted vertically or at say a 45* angle shooting from stage left rear, to stage right front and two more centered, yet still left and right on a more horizontal plane directed out to hit the center of the dance floor and then run them on a chaser where they can either chase, or be a full on deal. You could also use many combinations with a decent controller.
While this is a very simple thing to build, it can really make a very cool effect on a wider stage. It can also be used on virtually any sized stage and the looks and angles can be tweaked by postioning the whole rack or even individual lights in different positions.
I must say, on a very fast chase it really looks cool.
Just a thought...