Eric,
If we stick with Ruth, do you have any preference as to the time period with his career?
Here are some nice shots of him with Boston that would fit the size really well:
And a nice one of him with New York in 1921:
Just some suggestions.
For the record, I don't know if it was one you were seriously considering, but the shot of him with all of the kids faces would probably be too much for a 20" x 28" canvas, but if you had your heart set on it, then I'm sure we could work something out.
Either way, hope this gives you a couple of ideas!
Graig