We just got back and saw the Power Rangers, too. In fact, we were at MGM 2 days last week, and saw them both days! They stay out for quite a long time. After being introduced, each one runs to a different spot in that big open area by LMA, so that five lines can be formed to see them. It's very organized, and the lines are fast.
According to my sister (who knows her Power Rangers!), the ones that appear are the Green Samurai from Ninja Storm, the Lone Wolf from Wild Force, the Red Ranger from SPD, the Pink Ranger from Time Force, and the White Ranger from Dino Thunder. Here's a picture of one of them (if it works).