Brant, I'm no expert but I think you can get some more depth to the milky way if you take longer exposures and stack them. 15 seconds might not be enough for the faint light from the milky way to register on the sensor, so it just stays dark in the result. I am also going to try to do a bunch of starscapes this summer, and if I can afford it I will get one of the clip-in city light reducing photos. From the before/after shots I have seen they really make a big difference, and also add a bit more contrast to the sky. Also I ran across this link a few weeks ago, lots to be pulled out of post processing, may be of use:

http://www.justinngphoto.com/2014/05...-of-singapore/