I would have to say that Uber is not a guaranteed contract, and you will be paying premium rates, since they won't have a return fare. I once had $100 taxi ride across the San Mateo bridge because they didn't have a return fare, and it was 20 years ago
​​We had a paralegal in our office who had an Uber no show to go to the airport after reserving a week in advance and almost missed her flight.
If you have a 12:00 flight and get there at 11:00 I would consider reevaluating that because the least hiccup, well I'll leave it that way.
You will have to drive down highway 29 from Napa, depending on where you are, across the carquinas bridge, down interstate 80 to the Bay bridge, and then traverse to the airport. You could spend 20 minutes just going across the bridge at that time of day.