First of all,
THE scary thread.
Next, I would speed up the Ghoul Fever's incubation to perhaps an hour, and then play up the angle. If a ghoul bites you, you get... hungry. You find yourself nibbling on your fingernails and then your fingertips. You can just... smell how tasty your buddy's skin is. Just so tempting to lean over and sink your teeth into him like an apple...
But it depends on how you like your ghouls. Mindless super zombies (like 28 Days Later or the Dawn of the Dead remake)? Pathetic and cowardly scavengers who only kill when they have superior numbers? Ugly vampires that eat flesh instead of blood (thus being the "poor man's Nosferatu")? Ruthless undead killers that just happen to eat their kills?
Now. One idea I liked is to have Ghouls try to act civilized. They wear fancy clothes (and masks), they have nice, well decorated table with fancy china - and a corpse on the table they delicately slice pieces off of and eat. The PCs could walk in to find them having a dinner party, but the meal has not arrived yet. The ghouls could invite the PCs to dinner (or mistake them for food).
Remember that Ghouls, like people, might also have certain food preferences. Some might prefer just the skin, while others could fancy particular organs, and so on.
Another approach is to go the "Hills Have Eyes" route. Ye olde Texas Chainsaw Massacre/Wrong Turn - the ghouls are malformed redneck cannibals that just Won't Die.
Recently I saw an interesting twist on ghouls in the show Supernatural: ghouls are like corpse doppelgangers. If they eat a corpse, they can gain the memories/personality of the person, and can take their appearance. So they could eat someone the PCs knew (or perhaps an ancestor), and try to mess with the party.
If you like that idea, but want to go a different route, the ghouls could go all Silence of the Lambs - skin someone and wear their appearance like a suit. Or use cosmetics to cover up their undead-ness; pretend to be a victim about ready to get chomped on, and then leap on someone, clinging to them and biting.
Ghouls don't just strike me as pack hunters and madmen - they also might make great serial killers. One powerful one could stalk the players, playing hit-and-run, or hunt them like an archer, running across the roofs of crypts. They could find the ghoul's lair, with trophies from previous kills.
The PCs could walk into a ghoul's larder; think a butcher shop, with chains hanging down and clinking coldly, insects creeping and bubbling, rusty, blood-crusty knives hanging all around.
Then, there's giving some ghouls different powers. Some might be shadow-related; darting in and out of shadows (via teleportation). Becoming invisible or quasi-invisible. Others might be fast and skitter across the ceiling (spider climb). Maybe give these damage reduction and regeneration. This way they do something different.
If possible, I'd sprinkle traps throughout the place. Not traps designed to kill - but to capture. Portcullises to cut off exits and herd the Pcs in one direction. Snares and traps designed to hold players still while the ghouls come after them. The point is to feel like the Ghouls are prepared, they're closing in on them, and these traps are slowing the PCs down and making them vulnerable. This is the Ghoul's playground - make that evident.