Blake said in another post that early 95's had vented rear rotors, while the later one's didn't. How much of an advantage would having the vented rears be? I know what the purpose is, but is it worth it to swap those on to a '97? Would it be a direct swap, or are there any other differences with the rear brakes? How would I be sure to get the vented rotors instead of the solid ones (How would I specify if I were to order them)?

IMHO I would say that venting the rear rotors is not going to be a huge advantage.... the rears really don't do enough work to get hot enough to make much of a difference.
A.

Mark, I have vented rotors on my 95 and it seems they don't fit on another 95-96 with solid rotors, so I don't think you will have luck with your 97.

Having rear vented rotors, is like comparing on having crossdrilled front rotors.

Difference SURE, noticeable not much.

This will be brief since I'm on a 14.4 connection in Beantown right now.

I looked into this when I ended up with a set of vented rear rotors by accident.

The vented rotors should cool better, but they also weigh more.

The quick answer is that AFAIK everything is different with the vented rotor setup. The calipers are different to accomodate the wider rotor, the cables and mounting points for the ebrake are different, etc. Based on a few experiences I've heard about, it's also harder to find pads and replacement rotors (especially if you or your vendor don't know there are two different types of '95 brakes).

The vented rotors are nice if you've got them, but not worth the conversion.

Besides, you'd be much better off upgrading your front brakes to AWD spec.