It's rare that someone can effectively retire from the rackets and live off their income without law enforcement going after them and live in splendor. One guy who's name frequently came up in other discussions was Gerry Catena. Paul Castellano lived in his White House, but LE was always on his back and he had concerns about his own people. In 1986 Fortune magazine had a list of the wealthiest mobsters that included Tony Salerno and Michael Franzese. Here's some other lists (not all have accurate information):

http://www.investopedia.com/financial-edge/0912/8-of-the-richest-gangsters-of-all-time.aspx

http://www.celebritynetworth.com/articles/entertainment-articles/7-richest-criminals-history/

http://www.worldfinancialblog.com/entertainment/the-5-richest-criminals-of-all-the-time/

http://newsone.com/1505845/top-10-richest-gangsters-of-all-time/