I'm from the US and obviously it's a big deal with young and old alike. There hasn't been one year where I haven't dressed up. What we've done at our place (in Australia) in the past is a jack-o-lantern and some decorations. (I know they're expensive but I want my kids to get into it.) We decorated for Halloween but went OS for Christmas the first year we moved in so didn't decorate. I'm sure the neighbors wondered what kind of whackos moved in!
Neighbors who don't have candy tell all the kiddos to come "to the house with the pumpkin". Last year we went TOTing for the first time and just left candy in a spooky box on the doorstep with a sign on it saying we were out but take a few pieces. I'm too much of a kid to not go with DD.
This year we'll actually be in the States for Halloween and I can't wait to show DD what it looks like when the whole neighborhood gets into it. Ours is slowly becoming that way but I think seeing hundreds of kids in costumes will just blow her mind.
She's Minnie Mouse this year and I've decided to go as pregnant Snow White. I'm thinking about making the people who ask me what I am guess which dwarf is responsible.
Once the twins are born the Halloween parties will start though! I can't wait! Love to see so many people getting into it.