East Bay Connection (800) 675-3278
Super Shuttle (800) 258-3826
Enterprise Rental Car – can be convenient as they will pick you up at the hotel and drive you to your choice of local rental centers (Dublin and Walnut Creek) to arrange for your rental car.
Kayak.com – Source to research other rental car options.
Uber.com – A mobile app, which allows consumers with smartphones to submit a trip request which is then routed to Uber drivers who use their own cars.