Lois Lane was only scatterbrained around Superman - the whole vulnerability thing - and then she was strong and assertive around Kent. At least, that's the way I saw it, and that's why I liked Kidder's portrayal. I thought she had the dual personalities going pretty well.

As for Hackman, what he (IMHO) highlighted about Luthor was this - his genius; his clever schemes; his pragmatism; and his cockiness. Whenever he unveiled a plot in the movie, I chuckled, and thought, what genius! Of course, the logical leaps that he makes in determining Superman's weakness to Kryptonite are rather dubious, but still...

And then when he revealed his motives, I'd laugh, but I'd also be amazed at how much sense they make!