The time it takes an acid to affect granite varies from granite to granite and acid to acid. A rule of thumb is to clean as soon as possible. Hard water will also etch the stone as well as acids from wine. If you should decide on stone, make certain that you go to the stone yard yourself and pick the slabs that will be used for your project. Don't rely on a sample.
Dark granite is harder to maintain than lighter granite.
On the other hand, DuPont Corian's Magna series offers a unique look and comes with a 10-year installed warranty. Corian seams are virtually invisible, and Corian can be repaired. You cannot maintain stone yourself as you can with Corian. The shine would have to be renewed by a stone mason, although it's unusual to see stone lose its shine.