Best Way to Get from Seville to San Francisco/US

I can't think of any way to answer that question for you. You simply need to do the research. Go to Google flights or your flight aggregator website of choice and enter the different options, check the schedules and layovers, factor in the cost of the AVE (and any other ground transportation involved), and determine what the cost differences and convenience differences are, weigh them out, and make your decision.

I prefer to take a train after a transatlantic flight rather than another flight. So, I’d opt to fly to Madrid and then take the Ave. In fact that’s what I did in 2017 and it worked out nicely.

We flew Sevilla to Madrid to usa.

At the time (2018) it was much easier to train from Sevilla to Madrid, overnight, then fly Madrid to SFO. We had a great last night in Madrid dining and strolling until midnight. We slept a few hours and a pickup at 5AM. Groggy, we slept well on the flight! You’ll have to research the costs and factor in “convenience”.

Only you can answer that question because no one else knows the details of what the itineraries are to your city.

If flying from Seville, I would want the entire flight on one ticket. Don’t do a cheap flight (like Jet Blue, etc) and then a flight to the US on a separate ticket.

That said, let’s say the price was similar between: 1) Train from Seville to Madrid, dinner in Madrid, hotel in Madrid, then flight to US and 2) flight from Seville with a connection somewhere. I would fly from Seville.

Trains from Seville don’t go directly to the airport. You will have to transfer.

There isn't an easy answer, and as others have mentioned, you need to look at your specific options and make your own decision.

I will say that: Timing of US-bound connections almost always means either a very early flight departure from Sevilla or taking the train the night before. Airlines might also offer late departures, but with 12-17 hour, overnight connections.

Definitely an airplane