This works better on wraps than sandwiches, since tortillas don't get soggy as easily as bread, but: Chicken, lettuce, onions, mandarin oranges, apples, and poppy seed dressing is my new favorite combination EVER.
Om nom nom, fruit in my chicken wrap. 8D (I suspect it would also be good with pineapples or grapes mixed in, or with some cole slaw, or with those dried chow mein noodle things-- but I haven't had the opportunity to try any of these variations yet. I will as soon as I get the chance.)