I actually enjoy the pairing of Kenpachi/Unohana, if it's written tastefully.
Yaoi-wise, I adore the Ichimaru/Ukitake pairing, cracky as it is, and I write it into my own fanfics simply because it's so obscure.
Good on you for attempting the Kenpachi/Unohana pairing. I'm going to check out your roundrobin just to see what it's like.