L.F.
Check out the tide pools at Corona Del Mar. I included a yelp link so you can find where to park and see the reviews of this beach. I think a five year old would get such a huge kick out of tide pooling.
http://www.yelp.com/biz/little-corona-del-mar-beach-newpo...
Balboa Island (my home sweet home for seven years) is a very quaint little tourist area. Main Street has lots of shops and a few restaurants. The restaurants are reasonably priced, and the Starbucks there has a nice clean bathroom. If you walk to the Balboa Ferry, you can pay some nominal fee to take it across to the Balboa Penninsula. For an additional fee, you can drive your car onto the ferry. The Fun Zone (ferris wheel, bumper cars, etc) might appeal to your daughter, but I found it to be cheesy as an adult.
Like the previous poster, I LOVE Fashion Island. It is a beautiful mall, and from top of the the south escalators, there is a gorgeous view of the ocean and Catalina Island. There are lots of great food options there from Wahoo's to Roy's to McDonald's.
The Sherman Library is a nice little distraction too, and I think it is free.
The beaches are very crowded around this time of year. If you do decide to go, try to get there before 10:00 am or it will be very difficult to find parking. Good luck!