My daughter planned her own party.
We were fortunate in that the grandmother of one her best friends lived in a condo with a clubhouse. She was able to get the clubhouse for us for $20. Since my daughter's birthday was in March, the pool was closed, but that wasn't really a problem. Ground rules were pretty simple - stay inside the clubhouse, put your garbage in the bag marked GARBAGE, put your soda cans in the bag marked RECYCLE. Parents were given a specific time to pick their kids up, since the condo had a rule about the hours the clubhouse could be used, plus we had to clean up after, and we didn't want to be there all night. Perhaps we're extraordinarily fortunate in my daughter's choice of friends, but many of them helped us with the cleaning up while waiting for their parents to arrive. Some of the parents even pitched in when they got there.
She invited the people she wanted to come, and told them to bring their favorite cd's. We bought pizzas, chips, and sodas. A lot of her friends are in theater, so they pretty much made their own entertainment. At one point, my daughter put on the soundtrack from "Rocky Horror Picture Show," and suddenly there was a whole roomful of teenagers dancing the Time Warp.
Because Jazz Fest was coming up shortly after her birthday, we gave her the schedule and let her decide which day she would best like to go, and gave her two tickets for the day she picked - one for her and one for a friend, plus a bit of pocket money for refreshments and souvenirs. Seeing two of her idols - Bob Dylan and Ani DiFranco - on the same day was a huge thrill for her.
At Jazz Fest, we picked out a meet-up spot, and she and her friend were allowed to explore the fairgrounds without us as long as they met two conditions - they were never to separate from each other, and they had to meet back up with us every two hours. My daughter her friend had their cell phones with them as well, and, a couple of times, they had been standing in a long line for food or drinks and were almost to the head of it when it came time to meet up. So she texted me to let me know that they were in line, and would be heading for the meet-up spot as soon as they got their items.