I love your Costus ... the flowers look like tissue paper! I have a Costus pictus as well ... it hasn't bloomed yet for me this year.
The only Ginger's I've ever noticed a fragrance on are the Hedychiums ... I keep sticking my nose in the others but nothing so far. I've also got the Shell Ginger, Alpinia zerumbet 'Variegata' but it will probably never bloom for me since it blooms on old growth. I love the leaves on them.
