I am staying close to the train terminal on a Friday and Saturday. I would like some casual and some nicer restaurant ideas. Is it the rule that restaurants are closed from 3-7pm?
We enjoyed Terme di Diocleziano at Via del Viminale 3/A. We ate there twice last year, and loved the food, location, and the staff.
We also enjoyed Caffe Wahington, Via Viminale 4. We had good pizza and seafood there.
If you need food at off-hours, you'll find a lot of options at the Mercato Centrale inside Termini Station. It's a lot better than the typical US food court, but it is crowded.
If you have been in Italy for some time and are ready for something other than Italian food, you might like the Indian restaurant Saaz at Via Cavour 162. I had no trouble just walking in and getting a table in early March, but I don't know how that would go at this time of year.