To make the vinaigrette: In a food processor, combine the basil, thyme, garlic, pine nuts, and vinegar. Process until finely chopped, scraping down the sides as needed. With the machine running, slowly add the olive oil in a thin stream. Adjust seasonings if needed.
To prepare the eggplant: Partially peel the eggplant lengthwise, leaving 1/2-inch stripes of skin. Slice the eggplant 1/2 inch thick, sprinkle the slices generously with salt, and let stand in a colander for about 1 hour. Rinse thoroughly, gently squeeze each slice dry, and pat with paper towels. Light a grill fire. Brush the slices generously with olive oil. Over a part of the grill that's medium hot, grill the slices until soft and cooked through, about 5 minutes per side.
Grill the bread slices until lightly toasted. Brush the eggplant, tomatoes, and the slices of bread with the vinaigrette. Assemble each sandwich with arugula leaves, eggplant, tomatoes, and cheese. Slice each sandwich and serve.