We are staying in Rome our last night in Italy and are looking for a nice hotel to stay in with our 5 year old daughter. Looking for at least 3 stars, and would like to have a really comfortable bed before heading on our long flight home.

This one's quite good, they'd add an extra bed for your daughter: http://www.aklesiasuite.com/

Or one more option, also with the possibility of an extra bed:
http://martinoaimonti.com/

The best thing to do is to go to booking.com, plug in your date, see what is available in 3stars and above, and read reviews. People's idea of what is a comfortable bed really varies, plus no point in having a comfortable bed if the hotel is noisy if noise bothers you. Booking.com will show lots of pictures of rooms, and sometimes seeing a room helps. Depending on your time of year, you might be equally concerned about air con or heat.

The number of stars doesn't say much about overall quality of a hotel in Rome (or most of Italy). Stars are awarded based on facilities (on site bar or restaurant, elevator, pool, business center) and staffing level. There are many delightful small hotels with only two stars, and there are some dumps with four stars.

I used to stay in a very clean and comfortable (although basic) hotel that had only one star. It had an elevator and air conditioning, but it was run by a family, and at night you had to ring a bell to get assistance or to get into the hotel. They also had one room that had the bath in the hallway. These two things, and maybe some others that escaped me, were enough so that they couldn't get more than one star.

Try ALBERGO DEL SENATO. Great boutique hotel right across a tiny street from The Pantheon. There's a fantastic gelateria next door. The hotel has a few jr. suites with a pullout bed that would accommodate you and your son perfectly. We've stayed there many times and really love it!

Sorry-- that would accommodate you and your young DAUGHTER!

We have stayed several times at Hotel Genio, at Piazza Navona. They do have triple rooms.

Byrd

Another vote for the Albergo del Senato...excellent location and hotel. Do yourself and the child a favor: pay the additional money to get a taxi to the airport.