My husband and I are traveling to Italy with our children (8 and 11). We are spending most of the time in Tuscany and Umbria and plan to take the train in to Rome for one day--arriving in the morning and headed back to our house in Umbria at night. It happens to be a Friday in August. I have open tickets to the Colosseum, which allow us to enter after 2 pm. Since we will be there on a Friday, the Vatican will have night hours from 7 to 9:30 PM. Since we will be arriving by train, the earliest we can get to Rome is 8:30 AM. Would it be better to head to the Vatican/St. Peter's that morning and see it first and the Colosseum in the afternoon, or go to the Coliseum at 2 and then head to St. Peter's and see the Vatican during the night hours?
Edited to add: I know it will be hot and crowded. I know this is not ideal. However, this is the time we have and we want to go to Rome for the day. If you have any recommendations (times to visit, tours that might help save time and be enjoyable for the kids, etc.) as to best accomplish this, those are most appreciated.