Nick lives in a bungalow that is placed in extreme contrast with Gatsby's mansion next door and the Buchanans' mansion across the bay. Daisy and Tom both seem to assert themselves as members of an exclusive elite class and their home serves as one vehicle to make that assertion clear. Gatsby, on the other hand, asserts his membership through his lavish home only to win Daisy's attention. For both Gatsby and the Buchanans, their mansions reflect their social position in the upper class and lifestyles of wealth and excess.
Nick's bungalow is much more modest, as is Nick himself. He comes from the Midwest, which is a much different world from the East. Though his family is well-off, his lifestyle is not lavish or boastful.
Myrtle and her husband George live in "the valley of ashes." Myrtle tries to live above her means and has the opportunity to do this through her relationship with Tom Buchanan. Their apartment represents her materialistic desires. However, her home with George is much less fancy.
To me, Nick's home is sort of indicative of his own character. It is a home that is nice enough, not shabby or anything. He is like that -- he is by no means poor. But it is not big or ostentatious. That's like him as well -- he does not try to act like he's a big deal.
Gatsby's house is also sort of like him. It is big and fancy, but somewhat lonely and empty. He is rich and has made it big. But, at the same time, he is lonely. He really wants Daisy and doesn't care much about anyone else. That makes him, to me, seem empty.