CC Attribution is a well-recognized way to quickly give permission to people to redistribute and remix your work, publicizing it and increasing its value in the process. Bloggers looking for more color for their posts might grab a relevant CC'd photo.
CC Attribution-Share Alike may lead to someone creating something that you can reintegrate with your original work, improving it. If you provide a dataset of 2D time-based points and someone makes a neat visualization of that, everyone is better for it.
This depends on your content. Things like photos or datasets will probably be reused and remixed more than, say, written content (which will probably be quoted and linked to regardless of license).
