Imahan is one of the most famous sukiyaki / shabu-shabu restaurant with many branches. You can find Imahan at Asakusa, Shinjuku, Nihombashi, and other.
Another luxury and definitely the best sukiyaki in Tokyo is Ishibashi in Kanda. Not only the quality of wagyu beef, but also their traditional interior is very pretty. I'm sure you will have unforgettable experience!
An article introducing Ishibashi: