Bjo is never actually visible onscreen (but in white in still shots). Mrs Wise is in a brown uniform. Susan Sackett is easy to spot. She's the tiniest figure (in a similar white outfit to Bjo's) up on the second level balcony.
Bjo Trimble's book, "On The Good Ship Enterprise", discusses the making of this scene in good detail, as does Dennis Fischer's two-parter in the old "Enterprise Incidents" pro fanzine. Off the top of my head, the close up male Vulcan is Scott Dwek, one of Grace Lee Whitney's sons. (IIRC, he's the one who's a pilot and used to give annual flight tests to Christopher Reeve.) The female Vulcan is a fan named JoAnn Christy. In that same front line, Bantam ST novelist Kathleen Sky is easy to find, as is fan-turned-media-journalist, Dennis Fischer.
The only rec deck fan to get a screen credit is Paula Crist. She can be seen fleetingly in a wolfish female alien makeup on the rec deck. Playing her own creation, called "Worene", Paula originally tested as bridge alien (the part going to Rhaandarite ensign, Billy Van Zandt). Gene Roddenberry insisted Worene was such a great alien she should at least appear on screen. Paula went on to become a successful stuntwoman in Hollywood and even played the baby brontosaurus in "Baby: Secret of the Lost Legend"!