Algarve is one of the most popular places in Portugal, and certainly one of the best in Europe to spend couple of days. It’s known to have some of the best beaches across Europe, amazing restaurants and certainly a wonderful time spent relaxing through the south of Portugal.
For customers staying in Lisbon, I do never recommend a day trip to the Algarve, and returning on the same day. And the reason is simple: it’s around 2h30m to 3h driving time each way, ending up spending more time on the car rather than actually seeing it, for around 5h just on the highway.
Instead, the recommendation would go at least to spend one or two nights in the Algarve, starting in Lisbon and returning to Lisbon. There are some great places to visit along the coast of Algarve, but my favorite is the area of Tavira, including places such as Castro Marim, Cacela Velha, and much more.
There are two recommendations I would give for first time visitors:
1) Get a private transfer from Lisbon to the Algarve, with 2h sightseeing tour on the way, at your choose, for any place in the Algarve. This would allow you to have a comfortable transfer to Algarve, ending at your hotel: https://lisbonprivatetours.com/transfer-to-algarve-from-lisbon-with-2h-sightseeing-tour-visit/
2) Second option would be a private trip to the Algarve from Lisbon (starting and finishing in Lisbon), including two nights in the Algarve with a private guide, to explore the region in three days, including Tavira, Castro Marim, Cacela Velha, Sao Bras de Alportel and Faro, covering the major highlights on each place: https://lisbonprivatetours.com/algarve-3-days-private-tour-from-lisbon/