I was staying in a tiny, tiny apartment in NYC—a long, narrow apartment—very cramped, small rooms, tiny kitchen area, not many windows. It was also pretty messy but I didn’t really care. Then I found out that some visitors were supposed to be coming. I rushed around trying to straighten the place but the this woman showed up—she was maybe about late 20’s or maybe 30—five feet tall or so—brown hair pulled back in a pony tail, black rimmed glasses—she was “in charge of the keys”. She was asking lots of questions—mostly about how things were working out with the apartment—but I just wanted to get the place cleaned up. There was a knock on the door and a whole group of people had just gotten off the subway and were here—several of my brothers, a sister in law and an adult nephew—they all come in. Mostly they seem happy to be there but not Matt, one of my brothers—he isn’t feeling well. I wonder where are they going to sleep? and the place is still so messy. Then there are supposed to be more people coming—people that I don’t know well at all—but no one seems to know why they are not here yet—cousins on my dad’s side. No one seems worried about that though. Brian, one of the visiting brothers, is going to visit his friend John in San Diego the next day. I ask if I can come too but he doesn’t answer. He doesn’t seem to want that.
More domestic drama (referring to the previous dream, which is also about a living situation). You don't say whether you actually live in NYC, or whether you ever have done, but whenever a dream is so specific about a location it usually means something. New York is the "Big Apple" and is a place many go in hopes of realizing dreams of fame or business success. In this dream you seem to know you are in NYC though you never leave your small apartment. So think of the apartment as you and NYC as your greater environment. Do you feel small and messy in comparison to everything around you?
In the dream you don't care about being messy until you find out you're going to have visitors. Interesting. This suggests you are comfortable with yourself as a person in the internal sense but also care what others think in the external sense. In other words, you're fine with your personal mess but don't want others to see it. Do you worry they will criticize you for not being "pulled together"? In particular, I have to wonder whether you are concerned about what your family thinks of you, since they are the ones who visit.
Your other visitor is this strange woman, the keeper of the keys. She is a representation of some kind of authority. Though she is not dominant or demanding (based on your description), her gentle probing of how things are working out suggests a kind of therapist. Someone is there, genuinely wanting to know whether things are okay, and you are too busy putting on a show for coming visitors to spare her the time. Here your subconscious is suggesting you stop and take a minute, do an internal check. Get in touch with yourself. Discover how you really feel and never mind what anyone else thinks.
I don't know about your real-life relationships with your family, but the fact that the majority of the crowd that comes to visit is happy to be there, in your apartment, despite the mess and the cramped conditions, points to the likelihood that many will not even notice your internal clutter. They love you, or at least like you, and accept you just as you are. But you do have one brother here named Matt who is not entirely happy because he isn't feeling well. So you must ask yourself whether Matt has problems of his own, and whether those are affecting you in any way. Does he need your help? No one else is worried about Matt, so maybe he needs someone to notice that something is wrong, and that person may be you. In any event, your subconscious is singling him out for some reason, so explore that in real life if you can.
And then there is Brian, who is about to jet off to visit another friend. You don't say whether you are also a friend of John's; is there any particular reason you might want to accompany your brother on this visit? Or are you only looking to escape, looking for a distraction? Review your dream and the feelings you had about this trip to San Diego (again, oddly specific—does the real John live in San Diego? Is there even a real John?). How badly did you want to go and why? Did you crave a change from the cramped apartment and grey city? San Diego is hot and sunny; were you hoping a trip there would lift your spirits? Did you want to see John? Spend time with Brian? Or did you just want to escape all your visitors?
Brian, however, is noncommittal, and you read his lack of response as unspoken rejection. Again, I do not know what your actual relationship with him is like, but you must ask yourself ever more questions. Do you wish for Brian's approval? Do you need his permission for something? Is there a lack of communication between you in waking life? A dream like this one requires one to examine the fabric of one's life, right down to the very threads as you explore the ways in which you are tied and woven together with the others in your world. Your subconscious is pointing the way by isolating Matt and Brian in particular, and also by situating you in larger context with your extended family. It is time to inspect and investigate those connections.