Portugal/Spain family trip: would you add Seville or Algarve?

Hi everyone!

My family and I are planning a Portugal/Spain trip and we’re super excited, but we’re stuck on one big decision.

We’re 4 adults flying from Toronto, including my parents. Planning around 12–13 nights.
The route is basically:
Porto → Lisbon → ??? → Barcelona

We definitely want to do Porto, Douro Valley, Lisbon, Sintra, Fátima, and Barcelona.
Now we’re deciding whether the 4th stop should be Seville or the Algarve.

Option 1: Seville
Porto → Lisbon → Seville → Barcelona
12 nights: Porto 3 / Lisbon 4 / Seville 2 / Barcelona 3
13 nights: Porto 3 / Lisbon 4 / Seville 3 / Barcelona 3

Option 2: Algarve
Porto → Lisbon → Algarve → Barcelona
12 nights: Porto 3 / Lisbon 4 / Algarve 3 / Barcelona 2
13 nights: Porto 3 / Lisbon 4 / Algarve 3 / Barcelona 3

We care more about seeing beautiful/memorable places than making this a pure beach vacation, but we also don’t want to exhaust my parents with too much moving around.

For people who’ve done Portugal/Spain: would you choose Seville or Algarve here? Did either feel like a highlight? Anything you’d do differently?

Thank you!