Hello! My family of 4 (2 adults, 15 y/o son, 12y/o daughter) will be in Portugal at the end of March. We will start in Lisbon, then take the train to Porto where we will stay for 3 nights. Knowing that we tend to be pretty "aggressive" sightseers and Porto is relatively compact, we are considering trying to include a day trip (by train). Douro Valley is probably off the table because our kids won't have a ton of interest. Braga or Guimares look interesting and easily accessible from Porto, but we are also very intrigued by Coimbra. Is Coimbra reasonable for a day trip from Porto? Would we better off with one of the other two and saving Coimbra for a future trip? Thanks in advance for any advice!
The best way to see Coimbra is to simply stop on the way between Lisbon and Porto. It’s about half way, and is an easy stop. If you leave Lisbon ( or Porto) very early, you could possibly do enough sightseeing to make it worth your time. Even better would be to stop for a night.
Both Braga and Guimarães are quite nice. Guimarães is more compact. Braga, especially if you see the Bom Jesus, would take a bit more time.