RGJ.com – The newest addition to Las Vegas’ resurgent downtown announced itself this week with a marching band, a ribbon cutting and, of course, showgirls. The , which actually opened its doors in late October, aims to introduce an element of luxury among the retro casinos that populate old Las Vegas. The hotel is one of several new businesses opening in the town’s long-neglected core. A collection of high-concept restaurants recently has remade the look of the blocks around the loveably tacky Fremont Street Experience. A private park built around shipping containers is expected to open next month, and after…