Lets do this bit by bit.
Neuro: incredibly easy to get. Well I shouldn't say incredibly, but when you look at the general stats for accepted residents you see it ranks somewhere between family medicine and pediatrics on difficulty. Obviously this sentence is less accurate for Hopkins Neuro (or whatever the top in the nation programs are) but you knew that.
Ophtho: Difficult, but possible, to get into through AOA. Rotating at AOA residency sites help a lot and from what I can tell it has the lowest average COMLEX score of the ortho/ophtho/uro trio. I've been told that rotating at any program helps your odds with all of them. Also: more or less impossible to get in the ACGME world unless you have a connection.
Ortho: Actually not all that hard to get into in the AOA. LOTS of spots, but you need to be good enough to qualify. Not sure how specifically rotations effect your odds, as you can get a decent enough ortho experience on gen surg at some places, but definitely rotating at places you're interested in is encouraged. Is possible, but very very hard to get ACGME ortho.
Uro: Probably the hardest to get AOA because it is so damn few spots and is pretty highly desired. 1/3 of the AOA programs will definitely not interview you unless you've rotated there, the other 2/3 may or may not have the same exact rule. Surprisingly: ACGME (technically AUA) is very DO friendly and if you're highly qualified (you should be to be considering this field) you should definitely consider rotating at AUA sites. They are known to take qualified DOs without any noticeable stigma/bias.
