On the Athens - Crete route, overnight ferries arrive at their destination between 5.00 and 6.30 in the morning. On the route to and from Heraklion in Crete, the Eleftherios Venizelos on the ANEK fleet is one of the biggest ships of its kind. Public areas and cabins are all of high standard. It includes amongst its facilities a cinema, internet cafe as well as a swimming pool and music club. Food on the ships is satisfactory.
All cabins have a shower and toilet.
If you choose a more economical fare you can buy a simple ticket and sleep wherever you find it most comfortable - or talk and play cards, watch TV with fellow travellers. Viewing passing ships from the decks or the occasional distant lights from an island, is another pastime. There are pullman style seats available. You can if you wish board the ship 4 to 5 hours before sailing and enjoy the experience. In fact at Pireas this gives you a good opportunity to explore the area, perhaps have something to eat, visit churches and wander around the port with views of ferries and their signs to various destinations.