Too late now, but yes...Hallowe'en is HUGE at Universal. Hallowe'en Horror Nights run several evenings in September and October...but not for the feint of heart!
Elaborate haunted houses,shows,scareactors walking around the park's pathways scaring people.Google or Youtube Halloween Horror Nights Orlando,you can probably spend a couple days looking at videos or reading info about it as the event has been an annual thing since 1991.
if you have 2 small kids in your group and want to celebrate halloween, you would find it more appealing to do it at Sea World or the motherland.
HHN in the Studio side is not something your entire family would enjoy together.
Since the halloween event is over for all parks in orlando, read up on it by googling. if you plan to do a halloween event in 2013, you'll find places that will be great for the littles.
1 park, the Studios. It will close at 5pm to normal guests on party days, FYI.
Small children do NOT want to be around this party. My 8 year old doesn't even want to be at the Studios during the day before the party starts, because they have big things set up for the parties, and just those areas scare him, even in the daytime. We won't be able to do a Universal trip during the time of HHN, to honor his request.
HHN is a separate event at an extra cost, like the WDW Halloween party, but again, NOT for children.