Portimão is a town without any must-see highlights but has a lot of nice places. I'm particularly fond of the many small parks. Sufficient shopping opportunities are there which you might prefer to the mainstream offerings of the large shopping malls.
Lovely town and in August they have a sardine festival which is a must to visit
The second major city in the Algarve has a huge beach, called Praia da Rocha. The city is not very interesting, massive construction, lots of restaurant and bars.
A nice town with plenty of shops and a new palm tree lined water front. Plenty of fish restaurants and we always like to make at least one visit to the cafe in the fountain square on the water front for an ice cream sundae. Also a good place to pick up a boat trip to go either up river to Silves or out to sea for dolphin watching or fishing.