About six months ago, my agent said something that really resonated with me. While I was having a typical neurotic-writer moment and wondering whether I should hedge my bets in this business by writing in a second genre in addition to romantic suspense, she said that she'd been chatting with an editor and the two of them had concluded that the authors with the best chance of making it big maintain a laser-like focus on one goal. All their efforts are directed toward achieving this goal, and it helps them to figure out which opportunities and avenues to pursue and which to let go.
This comment caused me to do some hard thinking about what I want as a writer. From the time I began in romantic suspense, I have had a clear vision of the experience I want readers to take from my stories and the ways I hope to grow within the genre. Chasing the market had nothing to do with it. I simply wanted to write the kind of book I most enjoy. I do have to take notice of the market and adapt accordingly to survive as a writer, but I can't (or won't) change who I am to do it.
As I attend the Romantic Times Booklovers Convention this weekend (and much of the week) in Houston, I find it helpful to keep the idea of "laser-like focus" in mind. So many writers seem to fragment their efforts, writing in multiple genres for multiple publishers, always chasing the latest trend. For some (i.e. "fast" writers whose natural pace has them completing three or more books per year), it has worked well, leading to success (though usually in only one of the areas). For others, it has led to exhaustion and burn-out. For me, it would probably lead to a prescription for Xanax and other anti-freak-out medications.
The trick, I think, is to figure out what works for you. Don't be afraid to experiment and adapt, but don't squander the gifts you are given trying to please everyone. Figure out your core audience and with everything you write, try to give them a consistent experience that will keep them coming back for more.