DH, DD16 & her 17yo best friend just did the tour on June 23.
Definitely bring the I.D. When I booked the tour over the phone in May, the person on the phone said they'd need it since they were not 18.
We even brought a letter from Best Friend's parents, signed & notarized giving their permission for their DD to take the tour. The CM on the phone said we should since the friend was not 18.
Well when we arrived for the tour, the CM asked them if they were 18, & they replied, "No". He asked them how old they were & they replied. He didn't ask for the I.D.....just told us we needed to sign the waivers.
But no way would I show up without the I.D.
He may have just taken their word for it because both girls were wearing their "Celebrating High School Graduation - Class of 2011" shirts I had made for them (actually a DISer designed for them!)