NB: Here is a paper the derivation of the ggplot styles: http://vita.had.co.nz/papers/layered-grammar.pdf

I would recommend using theme_bw(), which helps solve some of the problem with the gray background.

EDIT: This is ggvis: http://blog.rstudio.org/2014/06/23/introducing-ggvis/

This is news to me, so I'll look into it to see how it differs from ggplot2.

EDIT 2: It seems more like that the difference is that ggvis is more for interactive charts, but then it requires a dependency on Shiny, which is not optimal for blog posts.