I need to get to Lisbon from Granada to depart to US on 31 Oct. It does not look easy by train or air.
Is overnight train from Madrid the best? Or, is a bus from Seville better?
'easy' is take the bus you like with www.alsa.es to Seville and then with the same company on to Lisboa.
alsa bus web site does not show bus from Seville to Lisbon. Are there changes enroute?
Click on the small 'International' tab and you will progress. As far as I am aware, but there may be a break for the driver or a change of driver, non stop. Look under the itinerary for whichever journey.
Got it?
I note your extraordinary and ungrateful post elsewhere, considering the guidance I have given you here. You clearly had no knowledge of the subject to that posting, as you had none here, or the background.