When I take the boys out I don't bring many toys. Generally they play with the other kids and their toys. That tends to level the playing field a bit. Mostly we visit older kids who just accept the boys as they are (they normally all play on about the same level even with the age gap).
I don't go out of my way to talk about what they do, but if asked I answer simply and if they seem awkward change the subject to their kid. Most parents will happily talk about their own kid and that is a good way to deflect awkward moments.
I look at it this way, if they had autism I wouldn't go out of my way to tell people about it, but I certainly wouldn't avoid the topic if asked. If some of their symptoms happened to cause an issue I would explain the diagnosis as a reason to avoid the actions being blamed on bad manners or bad parenting. When Bear has a tantrum because of his sensory issues I say why he is acting that way if asked. If someone asks Brendan about school and looks astounded when he answers truthfully I explain that he has special educational needs.
Your kid is SMART. If you try to hide it I'm guessing she will notice what you are doing and wonder why it needs to be hidden. I would be very careful modeling that her abilities are not "ok." Unless you can give her an explanation that you feel comfortable with I wouldn't try to hide it. You might try explaining to her before hand that the other kids probably won't be interested in mazes and some of the other things she is, but that she should be able to find fun things to do that everyone will enjoy.
