Not Lisbon as we are spending 3 days there , best day trips out of cascais 2 adults 3 teenagers thanks emma
Taking the regular bus to Sintra is a big pain IMO. It’s, long, crowded and not a pleasant experience. There is a very new hop-on hop-off bus that will take you to places in Sintra. I saw it around town for the first time a couple of weeks ago. So, unfortunately, information might be difficult to find. You might want to wait until you are here, then try calling them. I’ve found there is a significant lag with companies updating their websites.
If there is any way you can find (and afford) a private driver, that would likely be the best way. Your hotel might be able to give you some names of people who do this.
No but might hire for a few days x
Sintra by bus - not an arduous trip in my opinion.
Also, you can take the commuter train to Belem. There are many interesting attractions in and near Belem ( see your guidebook). The kids may like the electricity museum, which is between the highway and the river, to the east of the Belem train stop. Take the pedestrian overpass across the train tracks.
Depending on the sea conditions, Boca do Inferno can be interesting, within walking distance from Cascais. Of course there is the Parque Marechal Carmona in Cascais - lots of attractions for younger children.