On my last cruise, one of the bingo prizes was a tour of the bridge. According to the cruise director at the time, they used to do bridge tours quite often, but after 9/11, I guess they scaled back considerably with security concerns.
2007 - Majesty of the Seas (Bahamas)
2009 - Enchantment of the Seas (Western Caribbean)
2010 - Freedom of the Seas (Western Caribbean)
2013 - Golden Princess (Alaska, roundtrip from Seattle)