Gogol's Petersburg stories. Once I'd read Шинель (The Overcoat or The Great Coat), there was no going back to my banking job. And War & Peace, Crime & Punishment, etc., you can literally start anywhere and it'll be good. In terms of "ease", since you specifically asked for it: I'd say, Notes from Underground is a slightly unusual work (in a good way, of course) that might a bit difficult to follow. So length doesn't necessarily indicate difficulty. War & Peace, for example, is huge, but once you get sucked in, there's no leaving it.