I usually write a song using the guitar or piano.
Working out the lyrics and chords.
Once I get the verses and chorus written I'll input the chords into BIAbusing the computer keyboard.
I try and find a midi style that reflects the mood of my song and use that as my style for putting in the chords and setting up the structure of the song.
I then record the vocals still using the midi style.
Once that's done I start looking for a RT style that fits the song or just start replacing midi parts with Realtracks.
The reason I start with a midi style first is Real Styles still don't generate fast enough for constantly regenerating the song over and over again till I get the chords and structure the way I want.
After I come up with the right RT arrangement I then export to Sonar and work on the vocals and add solos where needed.
I also do some mixing then convert to mp3 and that's pretty much it.

I've never tried the melody maker to compose music yet.
I'll have to give that a whirl sometime.

Tim