In blender, puree garlic, and oil until smooth. In large bowl, combine 3 tablespoons oil mixture, tomatoes, crabmeat, shrimp, rice vinegar, basil, salt, and pepper.
Cut bread into 1-inch-thick slices and brush generously with remaining oil mixture. Preheat grill pan over high heat. Grill bread slices 1 minute per side. To serve, spoon seafood mixture onto bread; top with cheese.