Our Amber Louise is the only one who freaks out with company, but she's doing better if we have just a few people over at one time; large crowds make her spastic. After people have been here for about an hour or so, she'll come out and visit. The slightest move from anybody, though, and she's gone again. Back to the bedroom and under the bed. (And since Mollipop and Tabby came into the house, Amber has gotten much, much better about being out and about instead of staying in the bedroom all the time.)
The rest of the cats? They're absolutely fine with pretty much anything that happens. On Christmas, there were tons of people here and the cats moved through the living room and kitchen, jumped onto laps and expected to be oohed and aahed over. While I was putting the finishing touches on dinner that day, I also gave the cats their dinner and they made their way through the kitchen and its mess of tables and chairs and all the people standing around and sitting, and they ate their dinner. They don't care one way or another. Even Tabby, who has to wear the e-collar from being spayed, took everything in stride. (And Mollipop only jumped on the table once.)
We had Rick's birthday party back in May and everybody wanted to come inside and see the kids. And the kids were more than happy for the attention. They just went from one person to another. While I was getting the food ready, people would come into the kitchen to help and they usually ended up paying attention to the cats. (We had put a sign on the kitchen door:" Please do NOT let the cats outside!" and everything was fine. We also had a sign in the bathroom: "Please put the lid down when you're finished! Meow and thanks!" 
) We did have all the cats back in the bedroom for awhile because I was worried about them getting outside, but people would come inside and then open the door anyway to see the cats and so we left them have the run of the house. They're pretty good about not trying to get outside anyway, but with that many people (and children), I was nervous.
Even when we had the guys here to install the French door in the kitchen and the bay window in the living room a few years ago, the cats were very curious. Not scared at all. We ended up having to put everybody in the bedroom with the door closed because when the guys took the old bow window out of the living room to install the bay window, the cats were curious about the large hole in the house!
So other than Amber, the cats don't scare and they're used to everything that goes on around here. I think we're lucky in that the kids seem to be very trusting and they know they nobody would hurt them.
