Six Flags Great Adventure's inaugural Holiday in the Park is both a spectacle and a treat. Although other Six Flags parks have featured a holiday event, this is a first for Great Adventure.   It's not only a great way to celebrate the holidays; it's a way to prolong roller coaster season in the chilly Northeast.  Upon entering the park, guests are greeted by a massive Christmas tree replete with lights.  The park is filled with glittering lights, seasonal fixtures such as a snowman through which people can walk, seasonal concoctions such as hot chocolate and special funnel cakes, a booth at which guests can have their photos taken against a holiday background, and many more attractions.  Six of the the twelve coasters are operating: Batman:The Ride, Nitro, Skull Mountain, The Dark Knight, Superman:Ultimate Flight and The Green Lantern.  Some flat rides are operating, including Sky Screamer.