Hey K.
We had a Halloween party for my daughter's class when she was in 2nd grade and it was a blast. People loved it because it was not a birthday party, just a fun time. We cleared everything out of our living room so when you went in the front door, you had to go through a little haunted house. The kids got blind-folded and let around the room; they had to stick their hands in various things and we told them it was braing, eyeballs, etc. They loved being grossed out. You can use melon balls for eyeballs, jello for "guts" cold cooked spaghetti for brains, etc. Might be too babyish for 9 year olds?
GAMES: relay, each team gets a bowl of eyeballs (draw on ping pong balls) they have to transfer the eyeballs from one bowl to the other across the room first team to complete wins.
Straw suck: use cut-outs of bats, ghosts, pumpkins. lay them flat on the table and the kids have to pick them up but suctioning them to the bottom of a straw, keep them attached and transfer them to a bowl (or witch's hat!) first to finish wins
donut contest; You use a rope or ribbon and string it across your room wall-to wall attach it securely with tacks or nails. Then tie long strings that hang down about every 15-20 inches. They should hang down to about the height of the average kid's face. Then you tie a donut onto the end of each string. you line up the kids and tie their hands behind their backs; then they race to eat the hanging donut with no hands it is a LOT harder than it looks and they scream and yell and have a lot of fun with it.
FOOD: make a bisquick dough that is not too sticky and color with green food color. cut up hot dogs to about 2 inch pieces. Wrap the green dough around to cover the dog, and on one end put half of a black olive. they are supposed to look like Frankenstein's toes. The kids loved them
You can make a red punch (Vampire's blood)and freeze plastic spiders an stuff in ice cubes and float them in the punch
Google the Food Network and look up Halloween Party Food they have a bunch of fun ideas.
We also did a pinata which was really fun; we did it outside.
Last but not least the thing I think they liked the best was dancing; we used the empty living room and turned up the music and they just went crazy, the whole house was shaking. Anyway hope these ideas help and hope you have a great time.