Planning a trip to Italy for April 2023. Want to visit Rome, Naples, Florence and Venice. Should I base myself in Rome and take the train for day trips to the other cities or should I plan to get hotels in each of the cities I want to visit?

Christa, 

Rome is centrally located in Italy and has the best rail connections. From Rome it is a 4 hour high speed train ride to Venice each way.  That's a lot of travel for a day visit.  I would suggest an overnight stay.  A very nice hotel near the train station is the Hotel Olimpia - https://www.hotel-olimpia.com/48 .  Both Florence and Naples can be done as day trips as they are only a little over 1 hour from Rome by high speed rail.  A good hotel that is near the train station and Metro in Rome is The Hotel Massimo d'Azeglio - https://www.romehoteldazeglio.it/en/193 .