Last time I did it (my ex-wife is hafu), I didn't find the rice particularly difficult, but yeah, from a variety perspective there is no real option: you pick 2-3 types of fish and mix them up in as many different ways as you can. You are effectively forced to prepare for 5-6 people minimum. This is probably why sushi, in Japan, was traditionally considered festive food, not an everyday staple: there is no way to make it well for a single family.