In terms of location which hotel in Rome would be better

Congratulations on your trip to Rome. How long will you be in Rome? What sites are you planning to see/focus on? What time of year are you going and do you envision coming back to your room for "reposa/siesta" (or cool off) in the afternoon? Also, are you traveling solo or with others? I stayed near Termini on my last trip and personally am not as fond of the area; it seems a little grittier to me than other areas. I was not traveling alone and didn't actually feel afraid but definitely wouldn't want to stay in the same area traveling solo. That said, it is very convenient to public transportation. This trip I am staying near the Vatican, however, it is less convenient for public transportation and for many is too far of a walk for visiting other major sites. However, I wanted more of a neighborhood feel and I wanted to be near the Vatican early in the morning. Trastevere is an area favored by some but I have not stayed there. They've got some neat places to eat and I have been to a cooking class there.

I often stay at the Selene the night before flying back to the US, when I depart from FCO. It's convenient because it's walking distance from Termini. The hotel is very nice, almost across from the Opera House. To go to the Centro Storico it's a quick metro ride from Repubblica or Termini. Many don't like the Termini area, and I also don't like the area north of the station. However that area is technically the Viminale area and it's better than other parts closer to the station. Don't know the Gerber or Arco del Lauro. Between the two, based on location alone, I'd rather be at the Gerber, primarily because it's very close to the Metro (Lepanto) and therefore you can easily get on the metro to reach Spagna or Barberini (Trevi fountain) or the Musei Vaticani (although you could also walk from the hotel to both the centro storico and the Vatican, it's only one stop). The area is also more upscale (you are in the Prati district). Trastevere is a nice characteristic area of Rome, however it's not logistically convenient to visit the other areas. It's a walk to everywhere and there is no metro there. If you aren't a heavy walker, I wouldn't choose that one. Based on location I would choose between the Selene (if you want to be near the station, for example to go to the airport or to take day trips out of town) or the Gerber (reasonably walking distance to both Vatican and Centro Storico).

It depends on how much walking you want to do and what kind of neighborhood you want to stay in. We really love Trastevere (pronounced almost exactly like "Trust Avery"), and while it's true that it doesn't have a convenient Metro stop, a lot of the sites in Rome aren't near a Metro stop anyway (the whole Navona, Pantheon, Campo de' Fiori area, for example). In fact, the Metro forms a sort of circle around the main areas of interest, and doesn't help with those in the center. I find the neighborhood around the Hotel Gerber to be too boring and sterile for my taste, but some people enjoy it. Use Google Maps Streetview to judge each area for yourself. That said, the main touristic center of Rome is fairly compact and can be easily accessed from any of those places through a combination of bus, tram, walking and the occasional cab at the end of the day. Consider getting a transit pass to make your life easier. Happy travels.

I am arriving in Rome on the 11th of May. I will be with my husband and my daughter for 4 days, then on my own for another 9 days. I'm not sure if I am going to be staying in Rome for all those 9 nine days. I may head out to Florence or Assisi or both? We want to hit the major attractions with emphasis on the Vatican area. There is a cost difference of about 10-20 dollars between the three.

If your interest is primarily the Vatican, I'd let that dictate your choice. It's wonderful to visit first thing in the morning, getting there before the basilica opens and entering when it's silent. You can easily use the Metro, buses, or walking to visit other areas.