October Spain Trip

Book MultiCity Tickets (not roundtrip) -- fly into Madrid and out of Barcelona. No need to go back to Madrid to fly home. That's what most of us do in Europe as not to have to circle back.

While you’re based in Sevilla there’s minimal time allotted to see it. I also wouldn’t want to visit Granada as a day trip from Sevilla. That involves at least six hours of travel. Assuming you’re going to Granada to see the Alhambra, one could spend the better part of a day visiting it.

Personally, I wouldn’t try to go from Barcelona to Madrid on the departure day. Too many things could go wrong.

Fly in and out of Sevilla and Barcelona. Skip Madrid if you can.
Granada is not a day trip from Sevilla. It takes 2h 45m one way and you plan on returning the same day?

Thank you!! Great points. Planning on spending the night in Granada. Then train from Granada to Barcelona.

The trip from Granada to Barcelona by train takes at least 6-1/2 hours (and that's if you're OK with arriving at 10 PM). I'd be taking the 11 AM train, which takes about 8 hours. I am no fan of flying in the middle of a trip, but you have very little time. I'd look at flights. Vueling seems to make the trip several times a day. Be sure you understand the cafeteria-style pricing and allow for luggage fees, etc.

It sounds like you are committed to flying R/T Madrid. In that case you will spend way too much of your 8 full days just getting from place to place. Hard a choice as it may be, Barcelona should be scrapped as the outlier. What time is your return flight from Madrid?
You could conceivably spend your last night in Cordoba (it's a shame to only see it as a day trip) or perhaps Toledo. The benefit of Toledo is that if there's a train interruption, it's only about an hour by taxi or private driver to the airport.

I would go first to Cordoba, then Sevilla, Granada and Toledo. Or Sevilla, Granada, Cordoba.