Vina can't even be counted as an Orion Slave Girl. She was shown like that on screen for about 45 seconds, as an illusion created for Captain Pike as an ideal woman. Vina's true form, as played by Susan Oliver for most of the episode, was human...
...except at the end we find out her "beauty" is also an illusion from the Talosians and her "true" appearance is like this: 
So basically, the only time we actually see a "real" Orion woman ("green-skinned chicks" for the non-trekkies out there) is Marta. Who I agree with Field was hotter than Vina, unfortunately she was an inmate at an insane asylum.
The only other time we see an Orion girl in TOS is during the new "alternate timeline" ("insanely non-canon" for purist trekkies) movie, Uhura's roomate at the academy, Gaila. Unfortunately I can't find a good pic:
But she's played by the even more insanely hot actress, Rachel Nichols:
I love the funny story that was told when they were shooting the pilot episode with the scene with Oliver as the Orion Slave Girl. After they wrapped on the scene, they sent the film down to the development lab. When they got it back, Oliver wasn’t green, but normal-hued (for a Caucasian). I believe they reshot it, and when they sent it down to the lab, and it came back... normal-hued again. Incensed, I believe it was Roddenberry (or the director of the pilot) that called the lab and demanded to know why they kept sending back the film with her looking White when she was supposed to be green. Some old guy who answered was just as incensed. “Green ? Why didn’t you tell me that was the color she was supposed to be ? I spent all night working on the print making that poor actress NOT look like she was ill !”