One suggestion would be to spring for larger samples! I could never decide on a 2x2 size. Get at least a 4x4 or several 4x4s. It's worth it and you'll have nice coasters afterwards :)

The whitest white I could find was Okite Bianco Assoluto (absolute white). It is totally white with totally consistent finish, no dots, no chunks. I have thrown everything at my little sample, and nothing stains it. Hard p[art is finding someone who carries it. I live in RI and the closest place to me is in NH, but it's worth it to me.

Try Corian glacier white. It is a bright white and is the the least expensive of the line. The least expensive price I came up with is $35 a foot from lowe's in staten island, ny am doing the same thing white abstrakt ikea and glacier white corian for the countertop. I love a white kitchen.
Clean, simple and modern.

Ikea sells corian but it is more expensive than lowe's. If there is a home depot near you instead try them for the corian.