TWO TIPS FOR VISITING ROME
1. When you visit Vatican City, go to Vatican Museum first. The exposition finishes in Sistine Chapel. There are two exits from the chapel. If you use the one on the right side, you will get to the St. Peter´s Basilica directly without waiting in another queue. But you have to blend in some tourists group, because this exit is for groups only. Btw. St. Peter´s Basilica is for free and really worth of visit.
2. For visiting Colosseum you can do similar trick: buy a ticket for Palatino - Foro Romano. It is valid for Colosseum as well. And when you have the ticket once, you don´t have to wait in the queue in front of Colosseum a you go directly to the entrance.
These two tips can save you lot´s of time, which you can use for something more pleasant than waiting in a queue. Even though it wasn´t the main season, Rome was full of tourists this weekend and some places were so crowded, that it wasn´t worth visiting (the famous The Trevi Fountain or the Spanish Steps).