Nice idea! If you're going for ethereal, have you tried looking at the Ethereal from World of Warcraft? Not exactly like yours by any means, but the way they tackle that might be useful to look at. Maybe Dr. Manhattan a bit too, from the movie? Oh! Another fun thing to take a look at would be later scenes of Hollow Man. It's a bit of an old movie but there's a few cool scenes where when going invisible you actually see parts of the body within. Anyhoo, hope any of that helps!
