I found Lisbon in the main area to be a bit pushy. We got the Lisboa card, but read the rules, maybe it changed. For us we had to print something off, and since we bought it on vacation, well, finding a printer was a PIA. That was about 7! years ago.
https://www.lisboacard.org/
Good savings though. Take the old trolley up to Castelo de S. Jorge(their will be a line for the tram, and the signage is confusing but the ride up is fun), then walk down and grab food on the way down before you get to the busy square. Stop at Se De Lisboa on the way down as well, if you aren't sick of churches.
Transit is notoriously unreliable. We took it over to the Belem tower area. On the way back two trains hit each other, and we just walked back, it was quicker! The tower is super busy and skip-able if the line looks crazy. In that area see Jeronimos Monaster and of course Padrão dos Descobrimentos.
If it's a rain day and you want inside, the Museu Calouste Gulbenkian is worth a visit, just hop the subway. I think the card covered admission.
Sintra is worth the trip and an interesting story about brothers being brothers. While out, hit up Quinta da Regaleira. It's crazy crazy. Rich dude built a weird Disney like palace. It's kinda like the Enchanted Forest, but leveled up.
You should really go to Lagos! Such a great area.
Spoiler!
Quinta da Regaleira
Twisty trolly