Train, Bus or Plane

I have no comment on flights - but consider how few provide a review when they have had a normal flight.

What do you mean by 'stops'? The journey itinerary will or should be available if you are looking at the company websites - www.alsa.es or internorte.pt If you mean - will the bus stop for a break so you can stretch your legs - yes there is no doubt, as the driver(s) are required to break their journey.

I think I would fly that route - and this is coming from someone who will usually default to a train, if at all possible. RyanAir flies it. You'll be okay with them...super low budget, lots of rules to follow about bag size and checking in for flight. Follow their rules and it should be ok...it's a a nice short flight.

Looking on Skyscanner http://www.skyscanner.com/, that route is flown nonstop by Ryanair, Iberia, TAP Air Portugal, Air Europa, and SATA (a divison of Portugalia).

So you have quite a choice of carriers. But I agree, for such a short flight, how bad can it be? Do be sure to read all the fine print, so there are no surprises. A lot of bad airline reviews are from people who didn't understand the rules, or thought the rules wouldn't apply to them. If they say "one carry-on item only" they don't mean a suitcase and a purse. If they say a carry-on must weigh 10 kg or less, they won't let you take one weighing 10.5 kg; they'll make you check it, and pay the last minute check in fees, which are much higher than the advance ones paid online. One way budget carriers make money is to enforce all their rules strictly.

Do compare the FULL price on all of them before deciding. TAP and Iberia are likely to include one checked bag and have a more generous carry-on allowance, so when you add all the fees for the "budget" airlines, you may still do better with one of the "legacy" carriers.

If you choose the night train and want to sleep later, you can book it all the way to Lisbon (either Oriente or Santa Apolonia stations), arriving there at 7:20/7:30, instead of the 4:50 stop at Coimbra. A connecting train would get you to Porto before 11:00. Likely to cost a bit more, since you'd be traveling further.

Given the limited transit connections between Spain and Portugal, I would choose to fly. For budget airlines, you MUST follow their rules to the T. They make their profits on extra charges - that is their business model. And if something goes wrong, customer service isn't always top of their list.

If you do have plenty of time though, taking a bus or train would allow you to see more countryside (the train is overnight to Lisbon but daytime to Porto from there). But I'd only do that if you are not on a tight schedule or enjoy just watching scenery.