We (2 adults, 2 kids ages 9 & 14) are planning a day trip from Rome to Pompeii in mid-February. My tentative plan looks as follows:
7am train from Termini to Napoli Central, arriving 8:12am (or possibly departing an hour later, see comments at the end of the post below)
8:26 or 8:44 train to Pompeii Scavi on Circumvesuviana line, arriving either 9:02 or 9:13
I have reached out to Antonio Somma who is recommended by Rick for a 2 hour tour of the site. Waiting to hear back.
Assuming a guided tour from 9:30-11:30. Likely we stick around another hour and wander on our own.
Train back to Naples at 12:29 or 1:05, arriving at 1:00 or 1:36
The reason for a somewhat early return is that we would like to try to get some pizza at Pizzeria Trianon da Ciro for lunch, but they are only open until 3:30, and I assume we need to allow some time in case there is a line. Plus I don't think my kids will need more than 3 hours max at the site.
Have pizza/wine/beer to recharge, then either catch a mid-afternoon train back to Rome, or wander around Naples for another hour or 2. Considering we would have a super early start (and our AirBnb is about 20 minutes taxi away from Rome Termini train station), I don't think we will want to get back to Rome too late in the evening.
Alternatively, we depart Rome an hour later in the morning on the 8:00 train and start everything an hour later: 10:30 tour, then 1:41 or 2:01 train back to Naples followed by Pizza.
I am actually more partial to this slightly later start, so long as we have enough time to get pizza before the close at 3:30. Again, I have no idea what kind of lines to expect at the pizza place mid-week in February.