I have a G series, and find it easier to lug my SLR around when on foot, as it has a shoulder strap. I take the G when out on the bike, but it has to go in my backpack as it is too heavy & big to put in a quick access pocket. This is why I've just bought a little p&s for those quick take a photo moments.
As above, take a look at the Canon S100, and find out what your GF wants (SLR, 4/3, Lenses, Viewfinder, etc). Take her to a camera shop so she can find one that's most comfortable.
I have to say though, the quality of the images taken by my G is extremely good. It is also built very well and has a dent in the metal casing (no idea how), and has been in a few bike crashes too.