OK! I know this is going to sound a little mean spirited but I always thought of tipping as something you do because of extraodinary service above and beyond what was required. The exception, of course, being food service places where the base pay is below minimum wage.
At a place like Disney you already pay a premium price for the service. First you pay to get into the park and you can basically double that when you include the cost for the tours. The CM's used are supposed to be good otherwise word of mouth would eventually render the tour non-existant. I go to work everyday and no one "tips" me for doing my job. My reward is my pay and my continued employment.
Honestly, I am not cheap but these things can put such a strain on one's budget that it can break.
I did a KTTK tour and thought is was done well. The young lady that conducted the tour was doing it solo for the first time. We could tell when we occasionally caught up with the group in front of us that they were getting way more bang for their buck then we were. We didn't know at the time that this was her first tour alone. When we got to the end of the tour she was met by a group of co-workers and supervisors that presented her with her official riding crop. I know that no one tipped because there was way to much activity at the end to do so, but I don't think that I would have anyway because although she did alright, it was not extraordinary in any sense. We did all congratulate her and wish her well and told her that she had done real well considering how nervous she must have been. There was a planted "spy" in our group...I don't know is she knew that or not.