Trip to Ostia Antica

I think it is a bit much. It is really a good half day trip. You could not get there much before noon to 2 pm and it does require a change of trains. I think you would enjoy it more if you were not fighting jet lag.

Ostia Antica is a wonderful place that I still think about as one of my favorites when I am in Rome. Same day? Are you flying in directly from home (I see you are from Naples, Fl)? To me that sounds like a very long day after a very long night. Ostia is lots of walking after a couple of train rides to get there. Honestly, I reconsider doing it on your first day. Maybe get settled in, walk around Rome a bit and tackle Ostia another day. It really is worth the effort!

Thank you. I know, that I can always rely on very practical advice from this forum.
It's just we found a group walking tour around Jewish Ghetto that was cancelled on the day we planned and suggested another one that made me to think about switching a day trip to Ostia Antica to the very first day. O well, we'll just rely on Rick Steves book and podcasts.

Personally we don't do a lot the first day. Try to get organized and spend some time relaxing in the sun. We will drop our luggage and/or get into the room as soon as possible. Find a light lunch somewhere. Find the TI and buy any passes or day ticket that we planned to purchase. Run our schedule by a TI person and then maybe a good orientation walk of a couple of miles around the area. Maybe spot an evening restaurant. We generally take a < two hour map and plan the evening. For us it is a pretty unstructured day.

Depending on how you adjust to jet lag, I don't see a problem going to Ostia same day. We like to stay active, and we try not to nap at all, just stay up so we get on the local time. Bedtime would be a bit earlier than at home, say 9PM-10PM.

Ostia can easily be done in a few hours, it's not a full day trip. it's not as large as Pompeii.

If you arrive at 8, you can probably leave your luggage at your hotel, your room may not be available until later in the afternoon any way. If all goes well, you can be at your hotel from the airport in an hour or so.

Grab a light picnic lunch if you can at a cafe (a panini and a sweet) get to the Metro and go to Ostia for a mid day adventure, then return in the afternoon to your hotel to shower, change clothes, clean up, and if you feel the need, take a nap. That way your first day is not wasted, and you have seen a wonderful sight to start your holiday.

There is a cafeteria at Ostia, so don't worry if you don't bring food with you.

Personally, I wouldn't want to be that far away from my room on my first day. You never know how hard jet lag might hit. I like your idea of doing a self-guided walking tour nearer your room on your first day. Fresh air and sunshine will help you adjust to the time change.

And, minor point, Ostia Antica is actually a larger site than Pompeii. It's just that the part you can currently access is smaller and it doesn't feel as densely packed as Pompeii. Interesting article here: New Roman ruins site mean Ostia Antica is bigger than Pompeii