It's not a sandwich per se, but I like to take cold pizza in my lunch. You can be so creative with what you put on a pie and it usually always tastes great cold as leftovers. We make our own whole wheat crust and then just open up the fridge and see what we have to top a pizza. We have used BBQ sauce for the crust and then topped with tri-colored bell peppers, red onions, roasted chicken and cheddar cheese. Another concoction we tried was salsa for the sauce then topped with black beans, roasted chicken, jalapenos, black olives, tomatoes, mexican cheese blend. When we ate it hot we garnished it with lettuce, avocado and sour cream. Then, there's just the basic red sauce and cheese. Or, vegetarian is good too ~ olives, mushrooms, peppers, tomatoes, herbs, pineapple.
Innovative sandwich ideas for us basically consists of changing around the medium that holds the fixins. We use pitas, tortillas, rolls, savory breads in place of the basic wheat bread we usually use. Smear a whole wheat tortilla with PB, wrap a banana up in it. Stuff a pita with cottage cheese mixed with veggies like cukes, tomatoes, peppers, spinach. Whole wheat hoagie smeared with tomato-basil pasta sauce, then put motzarella or provolone cheese with spinach leaves, red onion, pepper rings, pepperoni or turkey pepperoni if you like.
Yummeeee.
But it's definitely not a good lunch to have if you intend to be up close and personal w/ sensitive sniffers! 
