I've never been on an overnight business flight, but I'd have no problem with it, to be honest. There's one colleague I travel with a lot, but we both know each other well enough to know when's a time to chat, when's a time to talk business, and when's a time to leave each other alone and read a book.

As for sharing a room, well, I'd expect better of a company I work for. I've shared rooms and beds with friends of both sexes (although I do prefer separate duvets) all over the world. It's just sleep...