You can uber to/from the airport. All of the wedding events will be 15 minute uber drives from downtown Sausalito. If you plan to visit sites around Sausalito such as Muir Woods or the Marin Headlands I would recommend getting a car.
Shuttle transportation will be provided from the Spinnaker to the CCC in Tiburon. The shuttle will pick up at the Spinnaker at 2:30pm and take guest to the CCC. The shuttle will return guests from the CCC to the Spinnaker for the reception.