I've done that in a few fics myself... wesleysgirl and I had a wonderful time in Saturation with Giles and Spike both bathing a feverish Xander and, if I recall correctly, having sex on the floor a few minutes later.

God, I love that fic... :;wistful::

And the way you describe it, I want a ficathon devoted to bathing with much silent yearning :-)