If you have trouble with dress pants falling off the hanger, you can use this slightly less traditional method of hanging to keep them off the ground.
To perform the Savile Row Fold, hold your pants upside down, with the legs straddling the hanger. Fone leg in through the hanger, pulling the leg all the way down so the bottom hem sits right above the crotch of the pants. Then, just fold the second leg over the first, and your pants should stay in place -- even if you give the hanger a good shake. Hit the link to see a full description.