I do enjoy spice in general - on donburi, mmm!:) - but I prefer maki sushi with fresh fish with a bit of the simple, fresh vegetables, like avocado and cucumber - for the pure taste, you know. My favorite "fancy" additions to the sushi rolls are all sorts of oriental pickled stuff, like makizushi no moto, marinated nameko mushrooms, and such.
Still, it's interesting to experiment time to time. Spicy souses, "funny" additions, like fried tofu, using smoked fish - why not, you never know what could be good, right? :)