These six islands are all within fairly easy reach of Athens, from less than an hour to five hours by slow ferry, with time cut roughly in half (and double the price) via the hi-speed boats, the latter also eliminating much of the pleasurable experience of being at sea and approaching an island.
These islands are rather different from one another, though there are wooded areas on most of them, and four of the five sizeable ones have beautiful harbors with neoclassical architecture.
The closest Saronic Gulf island to Athens, Salamina can be reached from the port of Piraeus by a combination of short bus ride and a ferry ride of a few minutes (if one goes to the port of Paloukia). There are two other ports (Ambelakis and Paralia) which can be reached by ferry from Piraeus in 45 minutes. The southern part of this island is far more appealing than the northern, with the nice village of Eandio, which has a pebble beach, pine trees, some bungalows in summer, and the island's best hotel.
The monastery of Aghios Nikolaos is in the southeast near Kanakia, with buses to it from Eandio and another road to it from the resort of Peristeria. Salamina Town (also called Koulouri) is in the north, 3 km from the port, but also on the water, with no rooms or hotels, no vehicle rentals, and an unappealing beach. More attractive is the Faneromeni monastery, located in a piney area on a peninsula to the north, up above the gulf between Salamina island and the mainland city of Megara. The church features a truly amazing painting of the Last Judgement; there's a taverna nearby and places along the shore below to swim. Psili Ammos, the village to the east has a taverna by the sea. The island's highest peak is nearbly. The islands resorts of Perani and Paralia are on the east coast.