While I write primarily novels and poetry, I have also written some half dozen short stories that I am pleased with. I've submitted them through the round robin of pro markets in the SF&F world, and none have been picked up. (Some personal notes from editors, though)
I know that some advice would be to continue to submit the older work to other venues and continue to write and submit the new work to the editors with whom you've had near misses.
But the reality is, I am not fully comfortable with the short story form. And while I appreciate a well crafted short story, I don't go out of my way to read a lot of them. I gravitate toward diving into longer work.
It looks like my options are to continue to write/submit, working my way through appropriate publications from pro to semi pro to amateur journals, both in print and on the web, or release the stories I feel are good enough as free reads on an appropriate venue as a way to build readership and share what I've written.
I think if I were more drawn to short fiction as an art form, I would probably choose journals and contests. I'm just not sure that's where I should be spending my time, rather than focusing on novel writing.
I'd appreciate any thoughts on the matter from both readers and writers.