I'm working on a novel featuring my series character Mike Christopher, but I believe I'm going to concentrate on short stories after that.
Part of it is that I've always had a tough time writing novels; I've found it's difficult for me to conceive of longer plotlines.
There's also a practical side to that decision. I've pretty consistently sold my short stories to science fiction magazines. Once I have enough to create a collection, I can self-publish that collection if I can't find a "regular" publisher to put it out. And unlike an unpublished novel, those stories will already have gone through the editorial process during their respective magazine appearances. So I won't need to go to the expense of hiring an editor before putting the book out.