Hi C.!
I also live in Huntington Beach and a TERRIFIC place to have that many people is Atlantis Park in Garden Grove....
Here is their birthday package for $90:
*Admission for 18
*Placemat, paper plate, cup, napkin, and fork for each guest
*Punch and ice cream cup
*Decorated 1/4 sheet birthday cake with child's name and candles
*Crown for the birthday child
* Birthday sign in Pavilion announcing child's party
*Eighteen invitations
*Table covers
*Two recreation leaders to lead games and conduct party
*Coloring book and balloon for each child
*Goody bag for each child
*Mylar balloon for b.day child
*Extra adults: $1 (admission only)
*Extra Children: $3 (admission, cake, punch, ice cream and goodie bag)
You bring your own food to serve. My friend did it this way.
I also had my child's birthday there BUT I didn't do the birthday package. I rented 9 tables (I had a BIG guest list) from them for just $5 for table for the entire day (10am to 4pm) so $45 total and then paid $1 per person for admission. They keep track of it at the gate. It is the cutest, gated park. Our theme was firetruck and we actually had a firetruck come to take everyone on rides throughout the local area but ANY theme or non theme is wonderful and as you can see, you can actually do a fairly inexpensive party at this park. You will not be disappointed. We also took a water table with us and filled it with bubble solution and bought 6-8 large wands for bubble fun. We had a parachute and did parachute games and had the kids bring costumes (a fun way to get another use from those Halloween costumes)that they changed into for a fun costume parade (b.day child leads!) and there is a wooden "stage" in the park as well as MANY unique slides, swings, etc.. It's just a FUN park to play at ANYDAY!!!
The Atlantis Play Center is located at:
13630 Atlantis Way
Garden Grove, CA 92844
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Check out this website for more information:
http://www.ci.garden-grove.ca.us/?q=commserv/atlantis
You have to reserve for birthdays through the Garden Grove City.
Good luck!!!
~R.