This is where chromecase has 'potential' I *REALLY* hope Google doesn't screw it up, opens up the api and lets plex, vlc, etc integrate to it, and that would be awesome.
Then my phone or tablet could be the remote to stream content to the tv, we shall see though.
For now my hacked apple tv and roku do plex fine. The main advantage that could be really nice for chromecast is it's price, nothing else. As you need another device to control it, which kinda sucks they didnt build a UI into it, but for $35 it would be amazing if they open it up. As of now I barely use it, only used it to try it out initially and found its easier to just use my xbox for now.