What is the best way to do 1 day in Sintra
when it comes to sintra i guess we all have our own favourites so if you haven't already seen these two links this should help you
how many attractions you can see in the day will depend on your own pace,how early you go and how you travel from one place to another but i would pick 2 or 3 which interest you the most and see how you go for time.
I visited 3 alone, which means I was faster than a group, and I found that it was more than enough. The itineraries stuffing 4-5 palaces into one day are way too intense. I recommend arriving to your first attraction at opening time to avoid crowds.
We went last Friday, arriving around 10am by train from Lisbonne. Walked the whole day. Went up to the Pena Palace (about an hour or so and it was so beautiful) then visited the park. As suggested here, we didn't visit the Pena Palace. Then, went to Mouros castle and finished by centro historico and with Palacio National. Had lunch at Sintra Terrace with a nice view. We were back in Lisbonne by 6pm. Amazing day!