I am from Portugal and have for the last 7 years traveled there with my twin boys. Since my parent still live there, we stay for the summer. 5 days is not all that much and with a 4 year old and the 5 hour time difference, it may be a little bit too much for him. I would go with just you and the husband do 3 days in and around Porto go to the wine country, and see the beautiful countryside then head to Lisbon and visit Sintra, Estoril and the surrounding areas.
Have fun.
Ahhh, just read the above poster's remarks -- sorry to pretty much say what she did.

No going out to dinner while leaving DC in the hotel room. Otherwise, have fun.

Bring! My parents took me to Portugal and I still remember the fun trip.

We spent a few weeks in Portugal last summer and LOVED it. I would leave child at home and have a nice trip with DH.

Stay at the Pousada do Porto, Palácio do Freixo if you can. It's an old palace on the river and just beautiful. Spend 2 days in Porto. I would then rent a car and drive down to Lisbon, but be sure to stop in a small, medieval town called Obidos along the way. It's amazing. There is also a Pousada there in the old castle (we stayed there), which is really cool. Then go to Lisbon. Outside of Lisbon, Sintra is really cool too and has some fabulous old palaces and castles surrounding it.

Alternatively, you could head out of Porto to the wine country in the Duoro Valley. Absolutely gorgeous part of portugal. Stunning hills with terraced vineyards dotted by small towns. We loved it there.

There are many options but I would agree with PP who says skip the beach. You can go to the beach anywhere, but shouldn't miss the beauty of Portugal's towns and cities and gorgeous countryside. Oh, and the people are wonderful, food fabulous, and wine great!!

Have fun!! We can't wait to go back.

on bringing the kid, it really depends on the kid. I fly to Europe every year and last summer (with kids 3.5 and 7) it was the first time they adjusted to the time in just two days (meaning going to bed at midnight and waiking up at 11 am or later for two days), in the past years we had 3 or 4 days with kids awake until 2-3 am and sleeping until 1pm the day after, a nightmare. also, they end up sleeping on the flight to Eueope somehow while I am kept awake by them, so when we get there and in the evening I am trying to go to sleep at 7pm (after been awake for maybe 30 hours), they are happily jumping around until 2am. so for a short trip, consider that the jet lag may be a problem, and if your kid is deeply sleeping at 11 am, you may end up been stuck in your hotel room

Portugal is really beautiful and not very big. Porto to me was different than the rest of the country, much more "british". I would not spend more than 2 days there, I would rent a car (we did, although we left from Lisbon) and drive around. there are really beautiful places worth the trip, especially Coimbra, Tomar and the templar castle, the Alcobaca monastry. I would live the ocean alone, I went in August and it was freezing cold outside of Lisbon (super hot outside) so I can only imagine how it is in May in Porto (but I confess I am from Europe and used to the warmer Mediterranean). But Portugal is so so beautiful that I would not waste days at the beach if I only had 5 or 6 days to visit. Lisbon also is worth a trip, and the complex of the Los Jeronimos, but I am not sure if you have time, unless you do only Porto and Lisbon. I relly envy you, I have been to Portugal twice and loved it both times.

I would leave him with Grandma - one of the best parts of Portugal was the drinking!! Plus, if you're like us, you will be walking everywhere and if your child does not like walking, then that will be a problem.

Alternatively, if you want to spend your time mostly at the beach then drive or take the train to the Algarve or hop on a flight to Madeira or the Azores. It should be great beach weather in May!

We flew from Newark to Lisbon and took the train everywhere we went. The trains were really nice. I have friends who rented a car and drove everywhere. Totally up to you, both are easy, but beware the driving is scary, from what I've heard.

My inlaws are from Portugal. They always fly from Newark to Lisbon direct to avoid transferring in Europe. I think that 2 nights in Lisbon would be nice. If your child is closer to 4 than to 5 and is laid back (ie he is ok if a vacation isn't 100% child oriented like beach or Disney) then you could take him. There is a castle/fort in Lisbon and I'm sure other stuff too. But given the choice, I would leave my 4 year old home!

Traveled to Portugal in 2005 pre-kids. Remember Porto as being very charming, very pleasant. We visited a port distillery, had some good meals (al fresco), and wandered around. You could spend the other 2-3 days in the nearby wine country or coast - maybe splurge at one of the luxury posada (sp?) hotels. I would think Porto/Portugal would be very welcoming of children, but I have no idea if you would find parks, playgrounds, or other kid-friendly diversions. I also remember our trip back (Lisbon-Heathrow-Dulles) was brutal - the fact that there is no direct service to Porto might make me leave child at home.

I'm thinking of tagging along with DH on a work trip to Portugal in May. He needs to be in Porto for 2 days. We could add another 3 days on either end. Any recommendations for how to do this trip? Would it be fun to just stay in Porto for 5 days? I don't want to spend the whole time traveling -- I know 5 days isn't enough to see everything anyway so I'd rather just enjoy the time we have and hope to come back another time to see the rest.

Also, we are thinking about bringing our 4-year-old, but we could leave him home with grandma if it won't be fun to have him. Would you bring him or leave him home? We do get to go away by ourselves occasionally so we wouldn't mind bringing him, but we don't mind leaving him either.

Thanks for any info!