Decor should be a cinch. Dark, moody room with black and red fabrics, coffins, spider webbing, candelabras (sp?), eerie music, etc. You can go classic, modern, or a combination of both. Change the white bulbs in your lamps to red bulbs. Get or make "plasma" bags (red koolaid) with rubber tubes.
You could rename the key rooms in your house with creepy names and signs: driveway is "Bat Parking Only. Violators will be Bitten
"; front door has either a castle door look or trimmed to look like you're stepping into a coffin; kitchen is "Blood Lab
"; main party room is "Mausoleum
"; bathroom is "Little Vampires Room
I like marsham's idea of the animatronic and projected movie. Maybe even put together a series of vampire clips from many movies, classic to current.
Alchohol involved? Almost any drinking game can have a vampire or scary twist to it. They usually get more fun as the night goes on.
Kids attending? Cookie decorating, dangling powder donut eating, pinata, treasure hunt, guess-the-gooey-material-in-the-bowl, spoon race carrying a spooky item, inflatable jump house, cup-plate-cup stack and carry, etc.
There are many good recipies for making ghoulish-looking food. Or make normal food and give it a scary name. A chicken finger, dipped in red sauce, tipped with a sliced almond looks a lot like a finger...