I have one-piece acrylic tops in each of my bathrooms.

Positives: Super easy to clean. Long-wearing. Mine were installed in the late 60s/early 70s, and though they do show wear (small scratches), they are still perfectly acceptable. No stains.

Negatives: Lack of customization - you must accept the available standard sizes.

thanks Mrs Pete

kohler has some integrated cast iron sink/vanity tops that look really nice... saw a couple in a showroom a couple of years ago....