I used the Archer sink because I preferred its shape, but I'm posting pix because I hope it'll help give you an idea of the size in a small vanity/bathroom. Before: 19" wide self rimming sink in 36" wide vanity. During: outside dimensions of 19 5/8" x 15 5/16" and inside dimensions of 17" x 13," also in a 36" wide vanity. Someday I'll have an "after" pic too! The faucet has been installed since this pic was taken. To me the sink size is just right for this small vanity. It could fit a kid's face but could not be used for sponge bathing, if your kids ever try to take semi-baths in the sink. I hope that makes sense. Blue

I don't think you're making a mistake since you're going with it for aesthetic reasons. I have the portrait suite in my downstairs bath (pedestal sink though) and it seems like you're using it for the look. IMO it's really just the plain drop-ins that have no style to them that look less expesnive. The portrait series doesn't "look cheap" to me. It's the whole package IMO, not just any one element. The type of vanity and countertop you install it in will have as much of an impact as whether it is undermount or not.

I was thinking about getting the Kohler Tresham drop in sink. It has a raised rim so I was thinking less water would get on the counter. I also liked that it already has the faucet holes in it so we wouldn't have to have the holes cut out. The bathtub and toilet are Kohler almond color so the sink would also be almond color. I like the look of the under-mount better and can get an almond in it. Thank you for your thoughts on this.

The problem is that the sink has an eased inside edge and not perfectly angled flat to fit against the underside of the stone. The fabricator should have cut the sink hole larger, to give more of a reveal of the sink edge, so that it contacted the stone where it is flat. This could be exacerbated by it not being a true undermount sink that is attempting to be undermounted. Or, it could be a hand made sink that isn't flat and can't be properly mounted without a gap. It's difficult to say exactly without viewing the installation in person.