I've done plenty of "his and hers" master baths where "his" was only a 24" or 30" single vanity while "hers" was 48" or more. But, the room design didn't depend on symmetry, just the overall visual balance that involved the other elements visually taking up some of the space. When confronted by one of those uber symmetrical spaces where equal sized vanities flank a tub with a window behind and it's all viewed as a whole from the door, you're going to have a much tougher time making that look good without sticking with symmetrical choices. Post your diagram of your space for some more informed choices to be suggested.

Thank you for your help! That's a good thought! Unfortunately, we've already primed the new drywall and have a single light electrical set up, so I think I'm stuck with a single mirror now based on the lighting. There also wouldn't be room for sconces on either side of the mirrors since the frames would be right next to the shower wall/bedroom wall if we had 2 so it wouldn't look as nice as yours!

pictures will help us give you more helpful advice.......... But a general rule for bathroom lighting is this: overhead lights too close to the face, cast shadows on the face and that is undesirable. So adding two more lights coming out of the wall above the mirror is not desirable and I'm thinking it would be overkill given all the other lighting you have going on. Furthermore, MCM calls for simplicity. Contain yourself ;) Plz send pics when project completed!

Sure, if you have the depth to do a deeper cabinet. Bathroom cabinets usually have 22" deep counters, and kitchens have 24" deep counters. The kitchen cabinet will give you a 36" high counter top. This is becoming more normal for bathrooms, but kiddos will need step stools longer. If this is a master, the 36" height is becoming normal.