I had what seemed like a pretty straightforward request: "After the user submits the form, we'd like the form to be Read Only from then on". Easy enough.
So I quickly added a new rule to switch views before submitting, but every time I'd open it up after it would revert to the "Editable" view, which happened to be the default view.
So if you just spin it and make your Read Only view the Default view, you can then go to Tools -> Form Options, "Open and Save" and add a new rule that keys off of something like an empty required field and switch the view to "Editable".
From then on whenever that form is opened it will remain in the Read Only view.