We just returned from a week in Rome with the family (two kids age 10 and 13).
Palazzo Doria Pamphilj was one of our highlights but it was not in Rick's book.
It is highly recommended and contains:
-Velasquez' Innocent X
-Bernini busts of Innocent X
-Caravaggio paintings
-many other paintings
Besides art, you can also walk through the palace apartments, which feel like a mini-Versailles.
The audioguide is free and had compelling narration.
Very impressive and a great option for a rainy day.