I'm planning on getting a hardwood plywood board to attach to an antique(ish) teachers desk so I will have a larger desk. The teachers desk is only ~2.5x4.5' and I'm looking at creating a 3x6' desktop.

My question is, with what should I finish the hardwood plywood? I want to keep/see the wood grain, and would like a finish that will be reasonably durable from day to day wear.

Thanks.