We just returned on Dec 16th from a month in the Med. and didn't want to spend our final day in Civitavecchia or Rome, but closer to the FCO airport. We also wanted to see Ostia Antica but Rick Steves only gave directions on how to take the train from Rome to Ostia Antica. I figured it out myself and highly recommend this instead of staying at port or FCO.
We arrived by cruise ship at Civitavecchia (we stayed in Rome prior to the cruise) and used Habicabs shared shuttle to get to Ostia. They agreed to drop us off at the hotel in Ostia instead of the airport.
We chose Fly Deco Hotel in Ostia, a brand new, absolutely wonderful hotel. The rate was under $100 and the room and breakfast was great. I have never seen honey from a honey comb at a buffet!
They allowed us to have our room at about 10:00 AM so we dropped off our bags and headed to the train station: Centro Lido. It is a 8-10 minute walk (use Google maps.)
Purchase a round trip ticket (6 Euros for RT, 2 passengers) Find the track headed back to Rome and go two stops and get off at Ostia Antica. Take the footbridge and path to the ruins.
The ticket 12 Euro pp. Purchase the map for 2 Euros and use either (or both) Rick's audio guide or tear out the pages from his book on the tour of Ostia Antica.
The place is perhaps better than Pompeii! It is larger and we felt we had the place to ourselves (almost.) Our photos are testament to that as none contain other people!
You can walk around almost every area (unlike Pompeii) and the setting is even more lovely. The huge pines are stunning. The signs are all in Italian AND English!
They have a very nice, rather inexpensive cafe and a well-stocked gift shop.
The return to Ostia was equally easy and the train came right away.
Because we were there at Christmas time, they had their town square all decked out and lighted. Not a Christmas market, but very festive. Remember that restaurants start their dining at 7PM. You can find a few who are open earlier but if you have your heart on Italian food, it is 7PM!
The next morning, their driver (for 10 Euro) took us to the airport. It was about a 20 minute ride in rush hour. We arrived in plenty of time for our flight. Easy peasy!