I usually reach for sparkling water when I want a drier taste. If friends are around and they like it a little sweeter, I go with sparkling soda.
Bitters are totally optional, but they add a nice extra layer. I stick to just a couple dashes—any more and the grapefruit flavor can get lost.
Fresh ice really helps. Old ice melts too quickly and waters everything down.
For garnish, a grapefruit peel twist looks sharp and adds a bit of aroma. Sometimes I’ll toss in a rosemary sprig if I’m feeling fancy or want a hint of herbal flavor.