Best of Spain in 14 Days October 23-November 5, 2023

Tough call. I guess it would depend on what you want to see in Madrid or Seville that's not on the tour and that requires some research and comparison. The tour's time in both cities is very short and pretty busy, so the likelihood of missing something of interest is high.

For me, the Mezquita is one of the most incredibly beautiful and evocative buildings I've ever been in. It took my breath away. But we did it as a day trip by train from Seville.

Assuming that you'd have your luggage with you, you'd need to leave it at the train station or nearby. It's been 14 years since I was there. At that time there was no place to check it at the train station. You had to take it to the bus station nearby. Things may have changed dramatically since way back then -- something else you'd need to research, along with Mezquita visit info and train schedules.

I've never flown into or out of Madrid, so I can't speak to that. However, I do like to spend my last night in country at or very near my departure airport. That's particularly convenient if you have an early flight since you have to be there 3 hours before the flight.

When I did the tour in 2010, I took the high speed train back to Madrid, stayed overnight in the city center at the tour hotel (Hotel Europa) and took an early morning taxi to the airport (hotel arranged it). I used the extra Madrid time to go to museums I didn't see on the first pass through Madrid (Reina Sofía, Thyssen-Bornemisza) and having one more serving of those amazing garlic shrimp at La Casa del Abuelo. I do sort of wish I had done the Cordoba stop over, but was stymied by the luggage storage situation as noted above (maybe it's more straightforward now).

Too bad you don't have time to do more. I stayed in Sevilla another night after the tour, then two nights in Cordoba and several more in Madrid before flying home. I agree with Lo about the Mezquita, one of my all-time favorite European sights, so I'd suggest the Cordoba option if you can park your luggage at or near the Cordoba station. A quick Google search suggested that there are ways to do that, you might want to look further.

The train will come into Madrid's Atocha station. I believe there's a bus with limited stops from there out to the airport. Depending on your flight time you might want to head straight to a hotel near the airport, or spend the night in Madrid and take a morning bus or taxi.

I think these rooms are the only accommodations located right at the airport. Other "airport hotels" are in the nearby town of Barajas, with shuttle service.

Cordoba is an incredible city. La Mesquita is a “must see”site. I am really surprised that it isn’t included on a two week tour. Take the train from Sevilla to Cordoba and later go to an airport hotel near Madrid. Your main issue will be finding a place to check your luggage in Cordoba.

Agree about cordoba’s mezquita. It was more impressive than the Alhambra in my opinion.
Anyway, there are companies called nanny luggage and radical storage that arrange with local businesses to store your luggage. They are all over.
There’s even one called cordobalocker.com