Santa Monica and surrounding area.

We were planning a March break trip to Costa Rica  but my wife went and fractured her knee so I am taking the two kids (15 and 13 yrs old) to Santa Monica for 4 days.   With the limited research that I have done I am planning to visit the Santa Monica pier, rent bikes and ride down to Venice Beach and beyond, take the Warner Bros studio tour and visit the Hollywood area.   I looked at Universal but not sure if if the kids would be that interested.  

 In the limited time that we are there other than what I have listed are there other must do / don't miss things in the area. 

Mike