Sorry, I took the inverted view of this. If you are inviting me, most likely I am an acquaintance.
I don't throw parties, but I do like to hang out, so generally I just invite friends over. Just friends. When I do throw a party, it's mostly for someone else and so is definitely mostly acquaintances.
> Maybe I don't really have any close friends anymore, the definition gets muddy when most everyone you used to consider a close friend is now a 12 hour flight away and you never really get to see them anymore.
Don't take this the wrong way, but this is depressing. Some of my good friends I have actually never seen in real life. Distance doesn't mean you can't be friends. But I do make a point to talk with them once a week (we game together) unless someone is gone on a vacation or something like that. I remember a time when I didn't have any real friends and it put me adrift. I would highly recommend that you try and give them a call, or shoot them a text.