Replace or Augment EF-S 15-85mm f/3.5-5.6?

[ham]

I'd either get a fast prime, or sell the 15-85mm and buy the 17-55mm.

I love the range on my 15-85mm (also on a 60D) too much to get rid of it, so I bought the 35mm f/2, and for street photography or indoors it's fine, it's even better for playing with shallow DOF. It's not perfectly sharp open, and the focus is a bit slow.

One thing about a fixed focal length, I've found how much I can get away with cropping images. 18MP is massive.