Skip the sunset from your hotel window. Meet at Cascais, head out with whoever turns up, catch the light over Cascais, and finish at Seafood in Cascais to eat.
An open meetup, not a guided tour: no guide, just people who want to see the sunset with company. About 75 minutes at an easy pace. It starts 45 minutes before sunset so you're somewhere good when the light turns, then ends at Seafood in Cascais. Dinner is optional and pay-your-own. Your photos from the walk show up on the page, and the next travellers decide to come because of them.
Bring Comfortable shoes, a light layer for after sunset, and your camera