^ Would be epic if they could use Green Lantern(Alan Scott) & Flash(Jay Garrick). Absolute Justice gave a great glimpse at the possibilities.
Now the JSA on the other hand could have worked towards that goal much better. Every season Clark runs into another member of the old JSA who teaches him a little bit more about what it means to be a hero. Season 1, WildCat actually teaches him how to fight, Season 2, Starman teaches him about sacrifice(dies in that episode) and on and on until from meeting these great heroes of days past he is molded into the hero we know he will be.
posted bringing 1 or 2 each season would have been nice. I am not sure how Smallville could do Power Girl but she would be fun to see live action.