While we have never used this ourselves as we are Premium APs, one of my sorority sisters came out West last summer and she and her family bought the Southern California City Pass
http://www.citypass.com/city/socal.html
The pass is good for 14 days and gives you 3 days of parkhopping at DLR and then you can also visit Sea World (assuming it still exists next summer due to Anheuser-Busch getting sold), the San Diego Zoo OR Wild Animal Park, and Universal Studios.
It cost $247 per adult, $199 per child off the website that I linked above, but it can also be purchased through Costco for a reduced rate ($217 for adults I think).
Assuming you buy at Costco, if you use all 3 days of your hopper and visit at least 2 of the other three attractions, you will get more than your money's worth!
Also, other posters have said this already, but make sure to take a day to visit the beach. Coronado in San Diego (home of the famous Hotel del Coronado which is one of the inspriations for the GF) is gorgeous and should not be missed if you head south.
I would also recommend checking out the Santa Monica pier as it is another pop culture icon.
http://www.santamonicapier.org/
Another great spot to visit is Long Beach. They have an AMAZING aquarium with these really cool looking sea horses that are called sea dragons.
www.aquariumofpacific.org And, the Queen Mary is permanently docked there. It is reportedly haunted and they have ghost tours set up...some in good fun with special effects and some that are more serious in nature.
www.queenmary.com
If you want to add some historical perspective to your trip you could visit the Richard Nixon Presidential Library in Yorba Linda. It is not very far from DLR, but feels like a whole different world.
My DH would be shocked to hear me say this, but SoCal has so much more to offer than just DLR and you would be missing out to spend your entire trip with the Mouse!