8 nights in spain

Eec,

I'd suggest choosing 2 cities for your 8 nights (7 days).

Madrid & Sevilla or Madrid & Barcelona.

If you opt to visit Madrid & Sevilla; you may consider visiting Córdoba on your way to Sevilla, or on the way back to Madrid, or as a day trip from Sevilla.

If you decide to visit Madrid & Barcelona, try to fly into one city & out of the other, to avoid backtracking.

Enjoy your time in Spain!

Agreed! 11 nights would be better for all 3.

Possible in 8 nights, yes. Desirable, no. Pick two of the three, and actually enjoy your visit. With such a short trip, be sure to fly "multi city," into one place and out of another, to avoid backtracking.

Note that the three all feel VERY different, and it's quite possible to have completely different reactions to each. Each also has multiple day trip options.

No, not desirable, but ...

Day
1. Arrive Barcelona (3)
2. Barcelona
3. Barcelona
4. Evening train to Madrid (2)
5. Madrid
6. Evening train to Cordoba (1)
7. Afternoon train to Sevilla (2)
8. Sevilla
9. Depart Sevilla

OR

Day
1. Arrive Barcelona (2)
2. Barcelona
3. Evening train to Madrid (3)
4. Madrid
5. Day to Toledo
6. Evening train to Cordoba (1)
7. Afternoon train to Sevilla (2)
8. Sevilla
9. Depart Sevilla

Schedule your travel in Spain's 'dead' early evening period before dinner - 6pm to 9pm.
Barcelona to Madrid is 2hr 45min by AVE.
Madrid to Cordoba is 1hr 45min by AVE.