Here's a strategy for getting rides on the good roller coasters at MGM Studios without waiting inn huge lines.

First, get to MGM Studios before the park opens. When you are there for the park opening, they tell you which cast member is the leader to Tower of Terror and cast member is the leader to Rock N Roller Coaster. These are the two big coasters that have long lines, so these are your targets.

Most people choose to go to the Tower of Terror first. So you should go to the Rock N Roller Coaster first to avoid them. If you hustle, you should be able to get there and not have to wait in any sort of line. Once you are done riding the Rock N Roller Coaster, ride it again. The line will still be small, and this will give it a little bit longer for the line to go down over at the Tower of Terror.

When you are done with your second ride, the line over at Tower of Terror should be going down from the initial flood of people. So head over there now.

Using this strategy, I was able to ride both coasters several times in under an hour. Not too shabby.