I recently read a comment from an editor that said there is a definite art to wrapping up a story. This same editor cited shabby third acts as one of the most common rejectionable offenses. I think there is a lot of truth to that maxim (more as a reader/viewer than as a writer), but I see the other side of the coin also.
A few years ago Stephen King took a lot of heat from his fans for The Colorado Kid. Readers were up in arms that King left the conclusion up to them. The same author was criticized a bit for his wrap-up to The Dark Tower, an ending whose infinite nature I thought was perfectly appropriate, given the complexion of the story arc and our hero, Roland Deschain.
Movies like A Civil Action, whose ambiguous anti-climax (Travolta shrugging, speechless, in a tight close-up) effectively captured the hopelessness of our civil justice system, and No Country for Old Men (an excellent film, across almost every critical criterion) have been taken to task for their open-ended conclusions.
In some cases (and I think this is the case for each of the four works I cited above) I think less is more. It's laudable for an artist to have confidence enough in his or her audience to glean "meaning" from the text without the benefit of overt explanation.
I had an editor request a rewrite on a story that called for a huge chunk of excised "showing" in the third act. His argument was, let's just let them see what they want for themselves. The audience can determine the horror more effectively than we can dictate it to them.
I'm in a similar place with a story I'm revising right now. I wrote a scene that included a blow-by-blow account of the vision in question, then I chopped it. I'm trying to leave the ending far more ambiguous, which allows for a little spectatorial creativity. One of the great strengths of writing horror, I think, is the subjective nature of the subjects that make our skin crawl.
Why not put that individuality to good use?
On another note, I received a personalized rejection on a story I sent to one of the "Big Three" fiction magazines yesterday. I've tried these folks a number of times, and it was gratifying to get a note of encouragement on my progress as a scribbler...