Prepare a grill for indirect heat: If using a gas grill, turn all the burners on high, close the lid and heat until the internal temperature is 400 degrees. For a two-zone grill, turn off one side. For a three-zone grill, turn off the center zone. If using a charcoal grill, remove the top grill rack and light the charcoal; when the charcoal is covered with ash, mound on one side of the grill. Return the top rack.
In a medium bowl, whisk the half-and-half, eggs, sugar, cinnamon and vanilla until blended. Transfer to a 9-by-13-inch baking dish. Add 4 pieces of bread and let soak 2 minutes per side. Transfer to a rimmed baking sheet. Repeat with the remaining bread.
Clean the grill grate well. Generously grease the grate. Working in two batches, place 4 pieces of soaked bread on the hot side of the grill, watching carefully to prevent burning, and cook until just slightly charred, 1 to 2 minutes per side. Transfer to the unlit side of the grill, cover and cook until the center is cooked and the bread is firm when touched, about 3 minutes more. Transfer to a platter; cover with foil to keep warm. Serve with the butter, syrup and Fruity Breakfast Sausage Skewers.