Coming back now that I've been able to read other replies:
Sally, it takes me a long time to get through a bottle too. Right now that is to my benefit as a lot of the scents I've collected are limited editions that aren't available for purchase, so I'm hoping they will last me a while.
Unfrumped, I love the idea of a signature scent too, and while I liked certain fragrances I never really settled on something that was totally me. Right now I think I'm happy enough having signature scent families, and collecting a group of fragrances to play with and layer.
My hope is that I keep the scent application low enough that I simply smell good or neutral to other people, rather than smelling like something or other. I love the idea of my scent being something relatively private, where you'd have to come in close for a hug to really smell it. I don't fancy the idea of leaving a vapor trail or a cloud of strong scent behind me. With subtler, lighter scents, at home, or when I'm outdoors more often I feel OK applying scent at my wrists or décolletage; in public where I'll be in close quarters, I'm more likely to spritz once lightly towards my legs, or apply a tiny bit of solid perfume behind my ears.