For families it is a great idea to stay by the beach - very few visitors to Rome remember the beach is so close by to the city.  The beach hotels and Hotels in Osita / Ostia antica tend to cost less and offer more space for families staying in Rome.  Ostia and Fiumicino is also a great place to take a walk at night with lots of shops and bars and restaurants.  The Roman nightlife moves to the seaside in the warmer months and Rome becomes more of a tourist scene at night.  From Ostia and Fiumicino there are public transport links such as buses and trains, and from Ostia there is the metro line to Piramide in the centre.  Another advantage of staying at the beach is the fact you do not have noisy motorbikes passing during the night and it is not so hot like the city during the evenings. With family vacations there is always the temptation to try and pack too much into one day which can be exhausting for little ones, so make the most of all the parks.  In one of the most famous parks Borghese Gardens you can hire rowing boats and bikes, or for smaller children try the pony and cart rides.  The Trevi fountain and Spanish Steps in Tridente are also sites that the whole family can enjoy, let them throw a few coins into the fountain or run up and down the steps, then treat them to one of the delicious gelatos.