From personal experience i don't believe that the blown in green fiber cellulose would have much effect that you're hoping for. Which i believe is foot steps and noise coming from above. The answer to sound proofing is mass. You want to put as much mass as you possibly can in the ceiling.
@Roy N. is correct that decoupling the ceiling and adding a second layer of drywall is the best bet. It should be the ceiling then a layer of insulation, roxul or any insulation, then another layer of drywall. Any contractor should be able to do this for you as its not very hard. Yes it will be more expensive than the blown in way but if sound proofing is your goal this is the way i would do it.
Also, either way will make a mess. Blown in insulation will shoot all over the place after the cavities in the ceiling are filled. So your tenants will have to cover everything or take everything out and the insulation will find its way into unwanted places.
check out this website and look at the bottom titled decoupling tips: http://www.greengluecompany.com/products/noiseproo...
