I don't know about other cities and I know Level airlines does not fly from many American cities. From New York to Barcelona you can find fares even cheaper then Jet Blue. I flew last year and the plane was brand new and comfortable. You can either buy food or bring food with you. Much cheaper to bring food. Plenty of movies and tv shows to watch that are no additional cost as well as adaptors to charge your devices.
I took Norse airlines last month from JFK to London for $100usd!!!!! No meals and my bag had to fit under the seat (standard carryon was an extra $85!!!!), but it worked. After touring London, I’m flying to SdC for $17usd. Yep, that’s JFK to SdC for $117usd IF you can limit your pack. I did and will buy anything else I need once I arrive in Spain, but I can’t imagine what that would be.