I have to agree with comments regarding the impurties of the sugar causing the crystilization. Also very important not to stir the water and sugar once it cooks, this greatly increase crystilization. The ice bath suggestion would definatly drop the temp quickly but your are sacrificing your pots pots and pans because your exposing them to 350 degress + to suddently 32 degrees (freezing temp for water) which will warp the hell out of them over time.
My suggestion would be to reduce the amount of water you are using and increase the temp in which you cook the sugar. Any time you play with boiling sugar the water needs to evaporate from the mixture. The more water you use the longer it takes for all the water to evaporate. If you want the sugar to be pourable after it cools you need to incorporate corn syrup! Any time you want your sugar to be elastic for turning into bows, center pieces, or various sugar decorations the sugar has to be elastic which is done by adding corn syrup. Try the following recipe and let me know how it turns out. 2 cups sugar 3/4 cup water 3 Tbsp white corn syrup (white only!!!)
Combine the sugar, water and corn syrup in pot or pan. Cook on medium heat until you see the color turn light brown (your sugar is now roughly 325 degrees...sugar burns at 350). Emediatly turn off the heat and place your pot/pan on a cool burner. The sugar will continue to cook and darken a bit more.