when doing flams, I find that the first hits should have a lower velocity that build up to normal velocity on the final hit. Also try filtering different ones ever so slightly. Another thing that works well is pitching the final hit up a little bit. Not anything too drastic, but definitely a couple tones or so.
Another thing, make a seperate channel for the snare thats doing the flam and put a reverb on it so it differentiates from the original snare. I find that panning the reverb or the flam itself somewhat to the side gives it a nice effect. I got some serious flammage in my most recent song (it's not a military march type flam though).
www.soundclick.com/5thsequence
it's called "Hip Hop"
The best flam work I've done so far.
Peace!!