We just returned from a week stay in Rome with our children (ages 6, 9, and 11). Our experience was so much better due to our airbnb experience!
When traveling with children, I highly recommend looking for an apartment. It's very difficult to find a hotel that can accommodate five travelers without being charged for double rooms (which may or may not connect). Further, having multiple bathrooms, private areas to go and decompress, and a kitchen for preparing breakfasts/leftovers are absolute musts for our family!
As to this particular apartment, it was large enough to fit all of us just fine, excellently stocked and decorated, very clean, filled with light and cheer, and while there is no dryer we did several loads of laundry with the washer and dried our clothes either in a bathroom or outside on a balcony.
Regarding mobility, you enter the building from the sidewalk using a locked door into a marbled hallway. From there it's either a few steps to small ornate metal "birdcage" elevator (which can fit up to four people in close quarters) or up four flights of marble stairs around the elevator. Then you enter the apartment's locked front door. The interior of the apartment is mostly flat (there's a slight ramp, like maybe 2 inches?) into one bedroom, but the hallways may be too narrow/sharp turns for a wheelchair. Actually, if you plan on using a stroller/wheelchair anywhere in Rome, I would advise rethinking this as the stone streets (which often times double as sidewalks) are generally not conducive.
Annie, the hostess, contacted us both before and during the trip to make sure we had everything we needed, including transportation from/to the apartment and airport. While she wasn't onsite, a neighbor was charged with letting us in and checking on us periodically which was perfect.
Finally, the location can't be beat. It's a corner apartment that overlooks the Tiber River, Trastevere, and the Lungotevere/Arenula intersection (yes, it can be noisy, but that's a given in a large city, so we simply used a white noise app on our phones at night). There's a great cafe right next door (Bar del Cappuccino), a small grocery right around the corner (Coop, which we stopped at every day for groceries and wine), an ATM next to the building entrance, and trams and buses right there on Arenula (which we never used but could come in handy). Campo de Fiori (we visited a bakery there almost every day) is maybe 7 minutes away, Pantheon (11 minutes), Piazza Navona (13 minutes). Piazza Venezia (11 minutes), Trevi Fountain (20 minutes), Colosseum (24 minutes), Spanish Steps (20 minutes), Vatican City (30 minutes), Termini Station (42 minutes).
Overall, this apartment was superb and I would highly recommend it to others!