Private Detective Couples

While I work on plotting a new screenplay, I'm also thinking about the next project. I'm pretty sure this will be a revisit (actually complete rewrite) of my first ever novel, written for National Novel Writing Month, which was (supposed to be) a bit of a thriller/mystery. I've often thought of taking an underlying theme of that, old cars, and building a series out of that. The idea appeals to me.

It seems that in order to really do that, I'll probably have to follow the herd and center the series on a single protagonist. As I thought that through, it sure seemed like what I was coming up with was yet-another-loner-hero. Is that what the world needs? Is that all it wants? Sometimes it looks that way. Even the women detectives I've read lately are almost just female versions of the same stereotype.

What if I did something different? What if I did a husband/wife team of detectives? How often has this been done? Is it too off the mark for the market? These are the questions I need to answer. I put part of the question out there to Facebook and Twitter and got a couple of answers from folks that are not really writer's market analysts. But they point to the only ones I could think of, too:

• Nick and Nora Charles from "The Thin Man"
• Jennifer and Jonathan Hart from "Hart to Hart"
• Patrick Kenzie and Angela Gennaro from "Gone Baby Gone", etc. (not married, but a couple)

Is that about it? I'm just getting started on the research. I know I don't want to spend much energy on this question, because it doesn't really matter that much. Except, I still wonder if it's different enough or too different.