It might strike as odd to say, but I don't see Slim as possessing hopes and dreams like the other characters. He does not hold on to the dreams of that which has passed, like Curley with his prize fighting. He does not operate in a world of hopes that have passed him by, as in Candy's failure to stand up for his dog. He does not lament the hopes that were deferred by others, like Curley's wife's love of "pitchers." He does not find himself animated by the hope of a promise in a distant future, like George and Lennie. Slim's aspirations are not like these.
Slim's hopes and dreams exist in the here and now. He aspires for the men he works with to be treated fairly and to be validated, as seen in how he rallies to Lennie's defense in his fight with Curley. His dreams are not illusions that are challenging to materialize. He is focused on making what he does valid, on working in an honest manner and not cheating anyone of what is rightly theirs. Steinbeck holds Slim in high regard for this, reflecting how Slim's vision of hopes and aspirations are fundamentally different than others':
His ear heard more than was said to him, and his slow speech had overtones not of thought, but of understanding beyond thought.
Steinbeck casts Slim's heroism as a reflection of "doing" and of being in the realistic present without becoming victim to it. This is where Slim's aspirations and hopes lie, in a state where individuals live to making their daily existence count in a larger scheme of understanding.