Do you know the manuf. of the existing cabinets? You'll have to match them if you want to reuse them to keep costs down. I'm assuming you don't want to have to tear out the granite, so the linen tower can only start on top of the counter.

IMO it's not going to be inexpensive and I'm not sure the results are worth it.

Mirrored frame added. New light fixtures

I would use the space under the vanity for a tall wicker basket to hold extra towels or laundry. I would leave the mirrors. The room looks "blah" because of the combination of tans, dark browns, and grays. If you are looking for a change, add colorful patterned rugs that run the length of each vanity - something with deep blues, gray, and tan.

bump