We are wanting to plan a trip to Portugal in 2023. We have not ruled out other places too (e.g. Spain)
Looking for Itinerary suggestions.. This is the start of my planning.
Pick up a Rick Steves Portugal book - great place to start.
Many of us use Lisbon and Porto as starting and ending points (open jaw - fly into one, out of the other). I did that with a stop in between in Coimbra and some day trips (Cascais and Sintra from Lisbon; also Nazarre and Tomar).
Our itinerary roughly was Lisbon, Evora, Obidos( do not stay there, just take a look for a few hours), Coimbra, Guimares, Porto. We did day trips from Obidos to Alcobaça, Batalha,. Make sure you visit Alcobaça and up the coast, Aviero. . We used those places to stay and visited other towns from them as day trips or en route from one to another. We spent two and a half weeks in Portugal, then entered Galicia, Spain and spent a month in Spain, ending in Barcelona. We loved Portugal!
More information is needed
How long is the trip
When is the trip
Who is "we" - a couple, a family of 5, two couples
What are your interests? Food, wine, art, nature, history . . .
I really don't want to come off as snarky, but you really need to do a little investigating on your own. Your question is too undefined.