Personally, I think you can go very, very wrong with angels, demons, hot sex, and ambiguous morals (hereafter referred to as ADHSAM). In fact, I think you should. Who wants ADHSAM that's right? It's like chocolate that's good for you - it misses the point.

If I'm going to do ADHSAM (or ADVHSAM), I'm going to make it a cheesy, popcorn affair. Anything less, and I'm disrespecting the genre.