24 Hrs in Rome before train to Pompeii, Sorrento hotel suggestions for Rome

Yes, Stazione Termini is in central Rome and the Naples station (Garibaldi) is also central to that city.

There are so many lodging choices in Rome that I don't know where to begin! Budget will factor in. I will say that for "walking the sights" you may want to target the Pantheon/Piazza Navona/Spanish Steps area for ambiance.

I'll be doing the same thing in October, and plan to stay near the termini train station at hotel Sonya.

I agree with Laurel about the walking areas in Roma & the fast train to Naples.
For Naples to Sorrento you have the Circumvesuviana (this includes stops at Pompeii). I would also look into Herculaneum (only if you enjoy ruins like Pompeii). If you decided at all to spend sometime in Naples, you should make a stop in the Old Town near Piazza San Domenico Maggiore for the Church of San Domenico Maggiore and Capella Sansevero http://www.madeinsouthitalytoday.com/cappella-sansevero.php it's a very close taxi ride from the train station.
When I did this trip last summer I stayed at the Four Seasons Hostel Rome, just a few blocks from the train station. That area is full of nice little hotels, restaurants and cafés for people watching. Also it was very easy to walk from there to the main site in Roma. And for the fast train it was very relaxing and easy to do (I used it both going down to Naples and coming back up).

You could stay in the Termini area to be near the station, but I prefer the Piazza Navona/Pantheon/Campo dei Fiori area for walking in the centro storico, especially nice at night.

With just an overnight stay in the Termini area if for no other reason than convenience. We have used Hotel Sonya and Aberdeen when staying several nights. For the quick overnight, as you are suggesting, we have used Hotel Contilla. Just a block south of Termini. Big advantage to Contilla is the self service laundry across the street from the hotel. Has an attendant so you don't have to do it yourself.

Thank you all for your wonderful and helpful advice.

Zoe can you suggest a quaint, small hotel in the area you rec(Piazza Navona, pantheon, Campo Di Fiori )
That won't break the bank?

To echo everyone here, all of our tours stay around Piazza Republica which is about a 5-10 minute walk to Termini station. If you prefer to stay near the Pantheon area you can take buses or taxis to connect the train station. The station neighborhood is convenient because the train from the airport goes direct to the station and your train the next morning leaves from there. I hope this helps some. Thanks all for your responses

Finding an inexpensive hotel in the centro storico can be a challenge. Recently I've stayed at Hotel Teatro Pace, a block from the center of Piazza Navona. It's in a good area for walking and dining, and includes breakast served in your room. A double in May is €110 per night (I like it enough to return). You can read reviews by recent guests on booking.com.

We stayed at the Hotel Select, quite near Roma Termini. This is the link: http://www.hotelselectgarden.com/index_eng.html. We walked just about everywhere from there. The proximity to the Termini for access to buses and metro was very handy. The breakfast was great. I just checked and prices for a double start at EUR 135.