In my opinion, a lot of usages are just that: my opinion.  I do think that some others are more than just my opinion; one usage would flow smoothly, while another would be so jarring that it would interrupt the flow of meaning significantly, which isn't good.  Not that finishing a book quickly is a good thing.  I know some people read books so fast that they only get the main story, and none of the more subtle nuances in how the story is told.

For instance, I'm just reading a story in which the Main Protagonist has come to the realization that she is not heterosexual, that she isn't going to have any success with a romance with a man.  She reports this discovery to her Mother, who eventually comes to terms with this new knowledge about her daughter. 

Meanwhile, the other main protagonist, also a woman--- I'm beginning to move from reading high school angst, to women discovering themselves in their thirties--- also ponders over her own feelings of not being straight, and decides to tell her mother that she isn't going to try romantic relationships with guys either.  Her mother too, eventually accepts what her daughter tells her.  (The two women had not yet met; I have to make that clear.)

So far, a fast and furious reader would gather that (1) there are two girls, both discovering that they're gay, and (2) each tells her mother, and everything is all right.  But there is a hidden subtext: one of the mothers is not only on board with her daughter's revelation, she is fully supportive.  The other mother has suspected her daughter's preference for a long time, and has been trying to set her up with handsome guys, hoping that one would take. The two situations are different enough to cast a long shadow on how the plot unfolds. 

So, on to today's post.  This is about "all right" versus "alright."  You can't use alright in every place where all right would work.  Not that you can't; it's just that it doesn't work equally well.  In the sentence "Are you all right?" my vote is for all right.  In the case of "Alright, let's get this party started," I'm with alright.