my two cents]
I couldn't agree more with mdwstms. When deciding where to do your away rotations, whether the program automatically offers rotators an interview shouldn't even be a factor in your decision in my opinion.
Think of it this way - no matter where you go, you want to work as hard as you can and make the best impression possible. If you do well and they like you, you will get an interview whether the program offers interviews to all rotators or not. On the other hand, if you do poorly, wouldn't you rather the program just not offer you an interview than waste your time, money, and effort by going to an interview where you have no shot anyways? Also, that would be misleading to you and there's the possibility that you would cancel a different interview(s) if one or more conflicted with the program at which you rotated.
I rotated at a program that doesn't interview all of its applicants and know some of my fellow rotators who did not get an interview there. I'm sure it's not the best feeling in the world, but at least they could focus their attention and resources on a different program where they might have a better chance.
I think deciding where to do your away rotations is one of the most important decisions in the 4th year process. If you work hard, are well liked, and make a good impression, you have a huge advantage over a majority of the other applicants. The program knows you well and often you will have a letter or two from someone in that program...again, putting you at a huge advantage.
Everyone is going to be looking for something different in an orthopaedic resdiency program, so you need to figure out exactly what you value most and target programs that offer those attributes. With that being said, you also need to be realistic in your goals. If you have low board scores, average/below average grades, little to no extra-curriculars, etc. then you need to talk with your ortho advisor to see where you would be competitive. Doing well on an away can definitely boost your chances, but some highly competitive programs still may not offer you an interview if you have poor stats.
Moral of the story: Figure out what is most important to you when determining where to do away rotations. Work hard and be optimistic, but also be realistic.
my 2 cents