As I'm married, I requested J-1 status and luckily the dept I'm headed to have agreed to sponsor me. As far as I am aware it is very difficult to get a J-1. I think most depts issue F-1 authorisation as a matter of course unless a J-1 is specifically requested. Even then, getting J-1 approval takes some persuading! I also think there's a limit (possibly 5) on the number of J-1s a dept can sponsor each year. Basically, what I'm saying is that you might not have a choice between an F-1 and a J-1 - if I wasn't married, I would definitely have gone down the normal F-1 route. Like you say, the main differences are for those who are taking spouses/dependents with them.