Tempo may be the key here (he said, pulling out his well-worn soap box
). Randomizing can get you only a short way to being non-mechanical. It can help a little, but only a very little.
Of course, I have no idea what kind of music you're working on, so the following may be fabulous advice or totally off the mark. I'm a big believer in elaborate tempo mapping to make a step-entered or heavily quantized MIDI arrangement sound non-mechanical and legitimately musical. We don't have great tools in Sonar (or any other DAW as far as I know) but we have OK tools. The tempo view gives you all the control you could ask for, but drawing in tempo is about as far from intuitive as you can imagine.
Take a look at the fit-to-improve process in Sonar. It's actual function is to take a performance freely recorded (without metronome) and align it with measure markers while creating a tempo track to keep the original timing. If your starting with a quantized MIDI performance already, you're not using it as intended but can still take advantage of it. Create a click track, one note per beat, lock all the existing MIDI tracks, apply the function, and unlock the MIDI data.
Or, wait a couple of months and I'll be posting a free conductor utility that you can use with Sonar to do this sort of thing in a more controlled fashion. Stay tuned.