UNLV has proposed a new stadium idea: LINK
Looks like 60,000 seats. It's a reasonable drive for Stanford, Cal, USC, UCLA, Utah, ASU and UA. Yeah it'd suck for Washington and Pac 12 north mostly but Atlanta isn't exactly close to College Station, Fayetville or Colombia,MO. That area of the country is spread out so I know a neutral site game is tougher logistically than say the SEC.