Sharing some tips from our recent experience. We are traveling by local transport with its attendant pros and cons. The Portalegre tourismo is very useful (thanks to Patricia). It is possible to take a bus to Marvao and Castelo do Vide in one day but too rushed. We went one day to CDV with a morning bus and later afternoon return. Plenty of time for a peaceful wander. The next day we left on an earlier bus to Marvao and returned around 1.30. This was shorter but the place is smaller and it was fine. Just be careful to meet that bus as it isthe last for the day!
The CDV ticket was from rede and an express. We were the only passengers. I bought return tickets from thebus station.the Marvao bus was a regional one and we paid both times on board.
It was helpful to have the printed timetables for both trips which I obtained by asking about them at t he bus information desk. He doesn't smile.
That gave us time in the afternoon to tour the tapestry museum without feeling too pressured.
We are traveling this time with a tablet which makes some things easy. But I cannot print tickets and the bus drivers need a physical paper ticket. The tourismo offered to let us access our email and print but in the end I booked with Mr Happy for our next leg, after checking times myself.
Hope this helps someone as I have been aided by the forum.