Having tried many different methods, including racking to Brite tank/'secondary' then dry hopping, hopping in primary after fermentation, hoppng in keg, I have to say my favorite method so far is tasty mcd's method where you add a lot of dry hops (2-3 oz for an apa, 4-5 for an IPA) at the tail end of fermentation in the primary for 2-3 weeks (I don't 'secondary' anymore). I find that the grassy/vegetal flavors are driven off but the good volatile oils remain. Add them when the bubbles slow to about every 5 seconds.