I thought Lois and Clark managed to cast 2 pretty good modern interpretations of Jimmy. I also thought that SR's worked out great as well. Heck even the fake Jimmy on SV played by Ashmore was fine.
Basically, this is a role we shouldn't have to worry about getting cast well. It seems like many types of actors can work in this role. I think the same can be said for Perry White.
Casting Superman/Clark and Lois... THAT is where we need the most importance. If you don't believe their chemistry/interpretation's on their characters... Guess what? Nobody gives a damn about Jimmy now.