The manuals for two of the guns I own (Ruger SP101 and T/C Venture) both state "dry firing will NOT damage the weapon). Both of these get dry fired w/o snap caps. All the other center fires get dry fired with snap caps. It has improved my trigger control and shooting accuracy many times over.
The question in my mind after a session has always been, Is it worse to dry fire a weapon before putting it away or leave it cocked over a long period of time?
Now, If I can release the trigger without dry firing (as in the case of a hammer gun) I usually do that.