You have received some great advice. I used to do the same thing. Then, as one gal suggested, I gave my son the opportunity to earn the privilege back.
Skip ahead to his middle school years: He would negotiate his punishments with me. Then he would turn around and do the same thing that just got him in trouble.
Now, he's a Senior. As far as kids go, he's pretty decent, but he still does bone-headed teen things (just like every other teen). This week he lost his car keys messing around. He tried to negotiate his punishment (Paying for replacement keys and grounded for two days - because he wasn't supposed to be out when he lost his keys down a Wal-mart storm drain). I nearly blew a gasket. I haven't been negotiating with him in years. Once I realized the mistake I made, enough was enough.
With my twins, what I say goes. There is no negotiating and if you misbehave you lose privileges, period. They know this. Since they were 4, 5, and 6. They had a few spells of testing the boundaries. Now they know better and they will listen when I tell them what the punishment will be.
I'm just telling you because the hardest thing we ever have to do as parents is follow through with punishments. It breaks our hearts making our kids miss something they've looked forward to for so long. However, giving in only teaches kids they can keep trying the same behaviors and when caught they apologize, promise to behave, negotiate their punishment, and then turn around and do the same thing. I know, I've been there.
Personally, I would find a sitter and take the others. Actually, I was in a similar position, but my husband ended up taking the twins and I had to miss out because we didn't have a sitter. It sucked, but it was a huge turning point in my then 14-year-old's behavior. The younger the child, the more they will push. But if you stick it out, it becomes easier because they learn you won't be swayed.
Just something to think about.