We return to Barcelona from Seville by train in the early evening and fly out the next morning. Any suggestions for a comfortable last night near the airport are welcome.
Yes... don't.
It's far better to stay in town, f.e. next to Sants station, which is where you'll be arriving to coming from Seville -several to choose from!- and then next morning take the airport train (barely 30') to the airport. You can use the opportunity to spend a night out in the area, choose a restaurant for a nice meal, etc... Also, depending at what time (and day) you're arriving, you could drop by La Font Màgica and see the show.