Long Beach has The Aquarium of the Pacific, nearby there's Cabrillo, and the Santa Barbara Museum of Natural History (1 1/2 hours drive North) has both a preserved moroteuthis and a really great architeuthis model!
As for eats, check-out Nova Express Cafe on Fairfax two blocks North of Beverly Blvd (across the street from Canter's Deli). Cthulhu resides there some of the time, and is featured on their t-shirts!
The Aquarium of the Pacific in Long Beach is definitely worth the trip. The Pacific Marine Mammal Center in Laguna Beach is a rehabilitation center for seals and sea lions (they eat squid...). If the tide is low, you should go to Newport Beach near Margarita Ave. and peek under all of the rocks. You could take a boat ride to Catalina Island. Let me know if you need any more information, enjoy yourself, it is a fun place to visit. If you eat fish Wahoo's fish taco is delicious (they serve other things besides fish...). Ruby's Diner at the end of the Seal Beach Pier is always fun.