Since I know some people might want to be left wondering, I'll put this in spoiler tags, but the lovely kind wise and fabulous mystery finally ended the suspense and told us whose bedroom it really was in Way to Go. Spoiler: What I Was Just Talking About Sara's. C'mon - like you're surprised? Though it should be noted that the bedroom was officially classified in the script as "theirs" even if it is her house/apartment. I can see that, though - because Catherine really will just walk right into Grissom's house, whereas I think Sara's place is less likely to be raided by co-workers at a random moment without some kind of call-ahead.