Don't ever forget the saying, you get what you pay for. Guys who have owned one or two LP's will always stand by the one they decided to buy, but having owned a friggin grip of Les Pauls, I can tell you that their pricing makes sense from low to high.
While the Studio's are a good entry into the domain of 'the real Les Pauls', both the build quality and tone are a few notches below a Standard and Custom. Still, very good sounding guitars, but they lack the tonal refinement that comes on the more expensive models. You only really notice it by A/Bing. That's not to knock the Studios, because they'll hold their own, but there's a reason they're $1200, not $2000.
The Classics were intended to be Gibson's answer to the "shredder" looking to get into a classic looking Gibson. They provided a faster, thinner neck and hotter pickups, and made the hardware the vintage early 60's type....with the wire retainer and less mass. The result was a very good guitar that was less well recieved by Gibson die-hards, mostly because the components equalled 'lesser tone' than the Stds and Customs. This is why I believe they priced them lower. After owning a Classic 60 in Bullion gold, I soon discovered that the pickups were useless to me, and the thinner neck resulted in a thinner tone, as well as fatiguing my left thumb muscle after a few hours of playing. At one point, I had two goldtops...a Std and Classic 60.
Both had a JB/59 combo, and the Standard had the better tone. I sold the Classic.
Moving along to the Customs....even many LP players stand by the idea that the Standard best represents the Les Paul feel and sound. The differences between the Standard and Custom are usually based on weight, headstock binding, and ebony board that comes on the Customs. They have a more 'in your face' bluntness to the sound and less resonant than Standards. However, the string to string balance is better and the articulation of the notes within chords is better.
All in all, I'd say most Les Paul fanatics choose the Standard Model, claiming that it's the perfect Les Paul. I tend to agree, and I haven't even begun to narrow it down to the fact that certain finishes sound different, as well as weights. The Historic division puts out some amazing Les Paul Standards, but even the best production models can equal them in tone and playability. Past the $2000 mark, you're really splitting hairs regarding preferences, but there will always be a player with a razor blade ready to go to work. LOL And most of them would be better off playing than splitting those hairs.