We are traveling from Barcelona to Granada and are debating about taking a vueling flight v. overnight train to save time. What is your experience with both modes of transportation?

we took vueling from Bac to Granada. Cheap. Fast. Perfect.
I hate taking trains for more than a few hours

I have flown on Iberia when they had a discount fare. Out of my Barcelona hotel at 9am, check-in Granada Hotel by 1pm.

My wife and I took the overnight train mainly for the new experience (it was our first overnight train). We had a full day in Barcelona before it left at about 9PM and we had nearly a full day in Granada after it arrived at about 9AM. It is not luxurious but the small berth with 2 single bunk beds provided us several laughs as well as an unexpected view of waves breaking on the beach as we enjoyed a glass of wine for a short part of the trip before going to sleep. We took an ambien to make sure we got some sleep and were refreshed for the next day. Would we do it again? Yes in the right circumstances but I wouldn't do it all the time.

I'm not a fan of long train rides so I take the plane. Ditto to what greg and danon have told you.