C.S.
There are really no play areas in between. We shoot for clean rest rooms and a place to move around. I have 2 boys ages 5 and 9.
In addition to Pea Soup Andersons (clean rest room - good pea soup - nice gift shop area - some room to move around), try:
1) Harris Ranch in Avenal. Clean rest rooms and nice gift shop area. Kids can check out the fountains in the gift shop area and hotel.
2) Top of the grapevine @ Fort Tejon State Park. The park is about 1.5 to 2 hrs from Long Beach. We sometimes picnic there on the way back. You can do the CA Junior Ranger Program also! This has become kind of a tradition for us. We have family in Southern CA. http://www.parks.ca.gov/?page_id=585
It's tough - not too much in terms of play areas. We have stopped at some fast food places. I recall on Carl's Jr with an outside play area. No good when it is 110 outside.
Good Luck!