Interesting that my experiences match those of posters above. The single best steak I've had was at Gibson's (I got lucky and snagged a table in the bar on a Friday night at 8:00pm with only a short wait). I also thought Prime to be good but not great (and the wines are outrageously overpriced, even for Vegas)

I like the cowboy ribeye at Ruth's Chris for its consistency, no matter which location, but have had surprisingly bad results at Smith and Wollensky in both NY and Chicago.