Woo boy, for the price of a new LP Standard I would MUCH rather have a used Custom Shop '57 or '58 RI. I'm not dogging Gibson, but I had a very hard time finding a magical Les Paul in their standard USA line. There were some good ones, some average ones, and some absolute lemons. When I started picking up some custom shop stuff mojo was there for almost every guitar...no lie. They are much more consistant and better built. Used '57s and '58s can be had for between $2400--$2600 used at places like The Gear Page or Craigslist.
That said, the now discontinued Les Paul Classics can be great guitars. I have stumbled across numerous examples that look the part, sound the part, and would only put you back like $1200. Again you'd have to play a few to find a magic one, but they do exist. Older the better for most USA Gibsons IMO because some of these new guitars feel like Les Paul shaped eggshells. They are so light and fragile feeling without any of the sustain and harmonics of the older solid guitars. YMMV this has just been my experience. When I was in the market for one it took me over a year to find the right one at the right price so be patient. Everyone who plays my '58 comments on how insane it sounds. I guess it doesn't really matter which model you get as long as the guitar speaks to you. Unfortunately for me I have extremely discriminating tastes.
'67 and '74 Fender Twin Reverbs, '74 Marshall 1987 lead mkII, Metro Superlead 100. Pedals from TC Electronic, Ibanez, Dunlop, BK Butler, Electro-Harmonix, Fulltone, Maestro/Gibson, Loopmaster switching, VoodooLab, Boss. Gibson and Fender guitars, Dimarzio pickups.