When to return rental car to sea tac

We r flying out of sea tac at 9 am on July 17 -Sunday. We will be coming into Seattle Saturday evening with a rental car. Should we return the car Saturday evening at the airport and take the shuttle to the hotel and a shuttle back to the airport Sunday morning or turn it in Sunday morning. With the tsa issues assume we should get to airport around 6:30 am. Thank you.

Return the previous evening. All rental cars at SEA are at a remote location now that require a shuttle ride. One less thing to do/worry about for your early departure.

https://www.portseattle.org/Sea-Tac/Parking-and-Transportation/Ground-Transportation/Pages/Rental-Cars.aspx

I've done it both ways. I usually allow a half hour to connect with the shuttle bus to get from the "remote" rental car garage to the airport. But either way will work.

With a 9 am flight and the TSA lines of late, I would return the night before. Does the hotel charge for parking? If so, that's one night you'll save. Remember to fill the car with gas prior to returning - another reason to do it the night before.

If the hotel shuttle runs both in the evening and at 6 am, then you've got your transportation covered.