Well, since it was pointed out that the previous threads had a distinct lack of diversity, let's try one that'll (probably) be all-female. Who's on your Mt. Rushmore of greatest game show assistants?
For the Washington slot, I would go with Roxanne, the assistant on the original Beat The Clock. Admittedly obscure now, but she was hugely popular in her day, and paved the way for future notable assistants.
For Jefferson, I'd put Carol Merrill. As LMaD's sole model, she had to have incredible stamina and range--showing off a new car in a dress one minute, then running backstage to put on overalls and play a hayseed the next. She became nearly as intrinsically linked to the show as Monty Hall, as evidenced by her guest model stint on HS's Game Show Week nearly 25 years later.
For the Teddy Roosevelt slot, I'd go with Janice Pennington. Every TPiR fan has their favorite model, but Janice gets the edge on sheer longevity.
And for Lincoln, of course, there can only be Vanna White. While other models became identified with their shows, Vanna is arguably the only one to become a bona fide star--to the point that even people who've never seen an episode of WoF could potentially recognize her.