I'm pretty new myself, but I can already say any modulation source (lfo's, envelopes) almost needs attenuverters/vcas to tune how deep the modulation will go. This is particularly true for voices that have a wide range of responses across a single knob (Noise Engineering modules almost always have wild responses to tiny knob adjustments, for example).
For attenuverters specifically, I think the Steady State Fate's Quad-Atten looks great. I have ALM Busy Circuit's ALM010 - O/A/x2 and it works like a champ for so many things (pitch before a quantizer, normal variables).