E.S.
Hi A..
My son is turning 9 this year. We have had a Halloween/Birthday party for him every year since he started school. We learned very quickly not to have it on Halloween, but close to it. Many parents want to take their kids trick or treating in their neighborhood or do their own thing. I would suggest having it the day after. They still get to wear their costumes, get candy, and have spooky fun. Kinda makes Halloween last even longer! You can have the party maybe 6-8 so you don't have to worry about it being too late.
We usually play games like pass the pumpkin (like hot potato with a mini pumpkin). Last year we found a game like pin the tail on the donkey, except it was something like pin something on the goblin, I can't remember exactly. Also we had a cd of spooky sounds playing in the background. We had small prizes for the winners. Also, last year I made green punch that had candy eyeballs floating in it. TOTALLY COOL!
Have fun!