FF Dagny is a sans-serif font. It goes well with Univers, Adelle and Stratum. If you're thinking about using FF Dagny then try 36px for headers. Give 20px a shot for content.
People commonly tag it as music, simple, sans serif, big, writing, app, design, photography, portfolio and blog. You can get it from Fonts.com, MyFonts and Typekit.