Bedroom for certain. There are arguments to be made for the shower being cleaner, but I feel the cons outweigh the pros (plus, who wants to taste shampoo when they're eating someone?)

The bed gives the pred and prey a nice comfortable place for all of their vorny activities, including the obvious benefit of the pred being able to sleep off their meal right then and there.
Plus there's something really nice about having your final resting place being your usual resting place~