There was no major surprise nor even a major victory at the box office this weekend. Disney's Race to Witch Mountain opened with $25 million, approximating exactly what it was supposed to do in order to get to number one.
The Dwayne Johnson family film had a really strong Saturday, and though every case is different, when Saturday is the big day in the weekend, that's indicative of a movie that might hang around a while. Usually, for whatever reason, movies that have a stronger Saturday in their first weekends tend to have more staying power, as opposed to a Friday the 13th,which made $19 million on opening day but fell out of the top ten at the box office two weeks later.
Watchmen rallied to take second place, although it would be more accurate to say that there wasn't enough curiosity in The Last House on the Left over the entire weekend to keep that horror remake in second place. You can hardly call losing two-thirds of your audience in seven days a success, and that's what Watchmen did, managing only $18 million in its second frame (compared to $55 million a week ago).