Originally Posted by
gfunkdave
...I've always seen cognac drunk from a snifter, which you cup in your hands to warm it slightly.
Cheap cognac is best drunk from a spherical snifter, warmed over an open flame -- that burns off the aromatics, which are not so pleasant in cheap cognac.
Expensive cognac is best drunk from a tulip-shaped glass (the same as used for fine scotch). Gentle warming from body heat to release the fine aromatics (which you don't want to lose as it is what makes that cognac so expensive).