I am more of a sushi purist, ok snob.
(Sushi actually refers to the vinegared rice. Maki are the rolls, and nigiri is the fish slice on top of sushi rice, and sashimi is just the fish slices.) I don't eat california rolls, that's not japanese actually. It's like egg foo young, it's a made up "japanese" food for western palates.
Eel sauce doesn't contain eel, it's to put on eel. It's most like teriyaki sauce but not quite. But I agree unagi is the best. But I actually prefer uni, uh hello, I named my dog after it! If you guys out there think what you've read about sushi is gross already, wait till you find out what uni is!
Anyway, each type of fish has it's own distinct flavor. Tuna and salmon are the easiest to start out on. Salmon is so rich and buttery! Still one of my faves. Mackerel is one I always stay away from.
I also stay away from chinese all you can eat sushi joints. I try to eat only at japanese owned sushi places (most are owned by korean) and yes there is a difference. Thankfully there are lots of asian markets around here, and I usually end up making my own sushi, it's cheaper that way anyway!
Now if I can only find a place to get fresh uni. Catalina is quite a trip....