You really need to go try Mashiko before you write off Seattle's sushi scene as inferior to LA's. I moved here from the Bay Area and found that the quality and variety was much better in Seattle, partly because the Japanese fishes are more easily gotten here.
The other difference I noticed when I moved north was that sushi is not such an everyday-dinner type thing, it's more of a special-treat thing, so perhaps the sushi places here don't have the sort of regular cash-dropping clientele to support buying/serving more obscure fishes.
Angelenos in general seem to have more income to drop on eating out than Seattlites do, as we don't have scads of rich/famous people out marauding our restaurants on a daily basis. :)

Mashiko usually runs about half a dozen or so sushi specials each day and three or so from the kitchen. you're probably not going to be staggered by the variety on one trip, but the specials constantly change so it's more geared to the regular customer-- And some weird stuff turns up. he often has the little fried river crabs, and will get in the live uni. I've only had sea cucumber at Mashiko, and once he had this long, skinny octopus that was tender enough to eat raw. Hajime said that they only come from the sea of japan and had no english name, and lord knows I can't remember the japanese name. Hajime has a loyal clientele of adventurous eaters.

But you know, the magic of Mashiko isn't the weird stuff, that's just icing. it's the unusual combination of flavors that they pull off in omakase.

If you go to Kisaku, note that they have a specials board, but it usually only lists the specials from the kitchen (which are good and creative). They have the regular stuff, and a small part of the menu that says "ask for availability", but then they always have a list of half a dozen things that aren't on the menu and are only mentioned if you ask. The server will always tell you about the appetizer specials, but you have to ask about the fish.

I haven't has sushi in LA, so perhaps I am sheltered, but I think that the selection at Kisaku is pretty good, and usually better than that at Shiro's. Though perhaps Shiro might just not like me, since I rub wasabi on each piece and then make a burrito out of it with pickled ginger. Just kidding. Though I did once take a friend from out of town to Shiro's and he used the ginger as a topping on his fish, and got his ass chewed out. I should have sat us at the bar. I'd never even seen someone do that before.

Anyhow, last time I was at Kisaku (3-4 weeks ago), they had pretty much everything on the "ask for availability" menu, including Aji, gizzard shad, and butter fish, the latter two of which I very rarely see. The Bonito and kampachi were outstanding. Off menu, they had moi, which I've only ever seen at yamasan in Bothell. and they had two types of raw squid. one were these little tender bite sized ones. Swordfish was off menu as well, and excellent.

You might want to give Kisaku another try and grill them for the specials.