Umi has a giant sushi train in the middle of it's restaurant in Darling Quarter. It's a very busy night and a bit of a wait but I think worthwhile.
Their udon dishes are tasty and very reasonably priced. There's the chicken katsu udon (with egg, splashes of seaweed, tempura flakes) and I also ordered the beef teriyaki spinach udon dish (with the same trimmings as the first udon). The sushi plates are good and consistent but I suggest you do a combination of main/sushi plates.
I also tried the dessert which was a warm green tea brulee and cold mascarpone roll. I thought the brulee was nice with a crunchy top and an egg-like soft bottom. The mascarpone roll was rock hard and cold. It was a rich roll but provided contrast to the brulee.
A nice dinner with some nice company :)
Prices: Udon dishes range from $12 to 15, Sushi plates are colour coded and dessert was $10