What I don't see, however, is a "third option" that I'd really, really want: the option, say, one day a week, to work in a shared space, with people related to my domain.
My company actually has an office that's in a suburb of where I live now. But it's inhabited by people who work in completely different functions and unrelated products. So going there would mean... I'd just basically sit there and chat with my coworkers online all day. Maybe have awkward superficial conversations in meatspace with a sales member, but I find the chats are just not very interesting, because I end up spending all my time explaining what I do, instead of actually having a conversation.
Again, what I'd love, is a shared space with other software engineers working on different products or tech. Sure, there are always issues of IP and privacy, but, I'd guess that the random watercooler conversation with someone tackling a very different kind of problem would be valuable. The added bonus of networking would be useful too.