it depends on what i'm going for. for a song like "chicken grease" on voodoo, i gated everything to get that tight "drum machine" type of sound out of the whole kit. but a song like "the seed" on the roots "phrenology", i probably didn't gate anything to get a real open sound.
but i'll use gates for overall control over the sound as well and not just for tight gating. gates really help me to fine tune once i get the main sound going especially the snare and kick mics. i'll use them sometimes to get rid of unwanted bleeding, noise or undesirable frequencies. eg: toms ringing out and making a tone which is clashing with some notes on the guitar. the SSL 9k gates work really well for me in conjuntion with the eq/side chain filters. i like the drawmer gates as well. but as with any processing, i won't use them unless necessary.