Family trip 1 week in March

Algarve will be too cold for swimming. Go elsewhere, unless you like hanging out with retired British expats.

You could possibly have some warm days but not warm enough to swim as the Atlantic stays cold until late summer. There are beaches closer to Lisbon you can visit but just plan on walking along the beach.
I would vote for Porto over the Algarve even if it were warmer.
Be aware that Holy Week is very busy with tourists as the Spanish like to visit Portugal during that week. So, if you don’t have accommodations, make reservations ASAP.
If you stay in the Lisbon area, you can take the commuter train from Cais do Sodré to Carcavelos or Cascais and find beaches.

Hello @stephanie.moleski,

I agree that you should pick Porto rather than Algarve... I'm from Porto so I'm a little biased, but as the others said, beaches won't be warm enough so you should consider visiting a city like Porto and get to know the beautiful historic centre, the gastronomy, the people, admire some of its monuments and feel its authenticity. You could still go to the Algarve, but I believe you won't enjoy it as much as Porto...

Enjoy Portugal ;)

I recommend staying in Lisbon. There are many things to do in the city, and a number of good day trips out of the city. Take you boys to the Quinta da Regaleira in Sintra so they can explore the tunnels and secret passageways in the garden. Also the electricity museum in Belem, the zoo in central Lisbon, and the aquarium. As mentioned in an earlier post there are nice beaches in Cascais, and there is a good park there for kids (Parque Marechal Carmona). In my experience traveling with kids that age, it is better to stay in one place than to move around.

Thanks for all the great input. What area in Lisbon is good to look for an apartment or hotel? I hope to be able to walk to main attractions?