The advice so far has been good and diverse. I just wanted to add one thing: whatever you do, avoid polyurethane finishes of the type used for furniture, as they inhibit the wood's ability to breathe and therefore end up damaging a pipe because of the necessary heat in the process of smoking it. As a minimalist, in general I prefer to sand pipes thoroughly, then finish them with a simple coat or two of Halcyon II or other appropriate wax to bring out the wood's maximum natural luster, but right now I'm using the shoe polish technique to be finished with a waxing perhaps.