I feel like I am the ultimate Smart Balance spokesperson but really they have some great products. They make a mayo that is fat but good fats and if you love your mayo its worth checking into. They carry it at most grocery stores (harris teeter, lowes foods and I think walmart even).
Also these might sound like weird choices for sandwhiches but you can give these a shot as well, I have totally altered my taste palette sense eating healthier.
Fat frees-ranch,blue cheese, french-All make great add ons to sandwhichs
Fat Free Cream Cheese-its all protein basically however adding jst a dab of honey and splenda gives it a little sweetness
Vinegars-Most vinegars have nothing to them, no fat, low carbs, they give a great flavor especially in wraps
Use your herbs as well, for example...
bowl>minced garlic>buttery spray>salt>pepper>basil>mix>add to toasted bread
The flavor is amazing. You will find after a while that just mayo can be bland once you get your taste buds going.