There is a technique I was taught in classical singing to add a brighter color to the sound. There are muscles in the face either side of the nose that for lack of a better word I'll call "snout muscles". If you learn to consciously lift those muscles while you sing (look in a mirror) you will hear that they change the color of the sound. That's one way to add a bit of variety. While learning a piece, my teacher would point out places where I should add that brightness to match the quality of words/melody to bring it out from the rest of the piece.

On higher parts of your range, lift the soft palate at the back of the roof of your mouth and flood the sound with air. That will give you another change. Sing a high melody without doing it and then try it, and you will hear that it changes the sound. It also makes it easier to hit those high notes and puts less stress on your larynx.

Changing volume to emphasize certain parts of the song also adds variety. If you come to a spot that is a tender meaning, make the volume softer. Practice the messa di voce exercise. On one note and one breath, start pianissimo and slowly build to forte then back to pianissimo. Do this exercise every day, gradually increasing the number of seconds. Count in your head as you build to forte, 1, 2, 3, 4, then as you diminish back to pianissimo, 5, 6, 7, 8. Keep the time it takes to build to forte equal to the time it takes to diminish again to your soft starting volume. This will give you more control over your voice and breathing, so you can build and back off from volume in a way that makes your singing more expressive and also adds variety.

Are these the kind of techniques you are thinking of? If you have the time to drive over to Bozeman and take lessons from Suzanne, she is very affordable and would work around your schedule, every other week, or however you can do it. She would give you the exercises and practice repertoire to achieve what you want to do and to build control.

Alice