We did just the opposite from Valpariso to Santiago. It takes a couple hours to do the drive. I would highly recommend flying into Santiago a day or two early and then taking a tour of the area on transfer to the ship. Valpariso has a number of wonderful sites worth visiting (see the PortReviews.com page on Valpariso) and we enjoyed a fabulous lunch in Valpariso (go for the swordfish everytime!)
You can book with a local tour operator to provide the tour and then to deliver you to the ship.