I was shocked to see how many people were standing in line to get into the Vatican Museum when I was these this past weekend. The line seemed to go on forever and it was 97 degrees out and very humid. Those poor people. If you plan on going to the Vatican, do no wait in the lines. Plan ahead and buy tickets online. For four extra euros you get a timed ticket and can walk right past the line.
If you cannot plan ahead (maybe you don't know when you can go), you will find MANY tour companies outisde of the Vatican who will get your past the line and give you a tour of the Vatican. I am not sure how good these tours are, but these were inexpensive and it's better than waiting for hours in the hot sun!
The same goes for the Coliseum. Outside the Coliseum we found several tour companies who formed tour groups on the spot and got you past the line. For ten extra euros we skipped the line and got an excellent 45 minute tour of the Coliseum and an hour tour of Palatine Hill and the forum. I know you can buy tickets at Palatine Hill to get into the Coliseum, but there was a long line when were there this weekend, so going with the tour was still the better choice. Plus, the tours were great!Edited: 21 July 2010, 17:51