Hi jestern,
You would be dealing with extremely tiny capacitance changes in an electrically and magnetically noisy environment. You might be able to make something you can play from ~1m away, but only with larger plate antennas, very stable oscillators, hum filtering, and lots of averaging / low pass filtering - the last of which would probably make the gestural response very sluggish. You could probably tailor the filtering based on the hand distance to make it response degradation less intrusive / more playable in the normal range, but >1m is definitely in the diminishing returns zone of hand & finger position data acquisition.
The useful maximum playing distance also depends on how you intend to play. My prototype seems to respond to my pinky finger opening and closing at ~1m, but if I "play" by waving my arm around the response distance is obviously somewhat larger. Moving my body around gives several meters of response.
[EDIT] And, as Christopher points out, at these larger distances you should probably be looking into alternative technologies to LC capacitance sensing.