Tilting at windmills for 15 years is exactly what happens when you have a superhero go up against a well-connected tycoon. Byrne and Wolfman wrote themselves into a corner when they revamped Luthor into a carbon copy of the Kingpin. Evidence doesn't stick, witnesses disappear, and they control their image through the media. There is no easy way to take a villain like that out unless you want Superman to either kill him or lock him away in the Phantom Zone. Otherwise, you're in for the long haul. Just look at how long it took for the FBI to take down John Gotti and for Elliot Ness to take down Al Capone.
To be honest, I prefer "business man" Luthor over evil scientist Luthor but I love it when they do combine both worlds like in the Bruce Timm DC Animated shows, he's a business tycon who happens to be a scientific genius. Of course they did that in the comics as well but I think the one that truly captured that feel for me was of course Superman Adventures, the comic tie in to the animated series and Paul Cornell's run on Action Comics, which is being collected in Superman: The Black Ring paperback.
Of course I'm not saying I have no love for evil scientist Luthor, I'm a big fan of the Eiliot S! Maggin stories from the Bronze Age that gave Lex a bit more dimension to his character, also Jerry Siegel used to write a very menacing Luthor who felt like a real threat to the world. It's just that when I read Geoff Johns attempt at bringing back that type of the character, it just felt bland (add to the fact, Johns had the tendency to push the whole "tolerance" angle by having Lex become a alien-hater) and the Silver Age, while not as bad, doesn't feel that threatening infact, young Lex from the Pre-Crisis Superboy stories felt more like a threatening villain to me than Silver Age adult Lex.