Thanks to those of you who made the suggestion though!
As much as we have grown attached to the affectionate names A, B, and C, we've decided on real names for the girls. We both love family names and decided to go that route, and had lots of great names as options. In the end, we wound up with:
Anna, Irene, and Brooks
Baby A - Anna Carolyn Nichols
Baby B - Irene Margaret Nichols
Baby C - Elizabeth Brooks Nichols
We've had these in mind for a few weeks and decided that we love them. I'm in decision making mode. Watch out.