One advantage to living in Arizona is that our kids are out of school at least two weeks ahead of the kids in Southern California. However, these tips work well any time of the year.
First, if you upgrade to the season pass buying 4 or more passes automatically upgrades you to Gold pass member. With the gold membership, you get free parking (saving you $18). You also get to enter the park 10 minutes early. Ten minutes may not sound like much but trust me, its worth at least a couple of rides on X2 or in our case three front row runs on scream.
Next that gold pass gets you a decent 15% savings on store purchases. How we used it was we bought 3 souvenir cups at the start of the day. Buying 3 saves you about $5 a cup, and with that gold pass you get another 15% off. So ours cost only $27 and change instead of $32. And 3 big drinks is plenty for 5 people if you share. The stands will also fill them with ice water for free if soda gets to be too much.
For accommodation, we like the Embassy Suites in Valencia. Breakfast is included (which is a big deal when feeding teens) and the rooms are big enough for 5. Two queen beds in the bedroom, a sofa bed and an air mattress with sleeping bag make this inexpensive and effective. Our goal was to travel cheap so we could spend more time. The money we save on an extra room more than makes up for meals out or souvenirs.
Some cost effective places to eat (compared to the park), the iHOP down the I5 and the Baja Fresh on Valencia Boulevard are family favs.
I am sure there are other ways to save money, but when you have 5 you have to think differently and different opportunities may open up to you.