Had the tasting menu back in Nov 2012.  The entire experience was heavenly, we paid out the nose but whatever, it was worth it.  If you must pick only one fancy dinner during your stay in Vegas, I'd vote for Joel Robuchon in a heartbeat.  Guy Savoy is a close second, and e by Jose Andres is in an entirely different category of fine dining so you should do that too... you know what? just do all 3 and let the kids pay for their own damn college tuition!