Thank you all very much for the excellent suggestions so far, and please keep them coming if you have anything else to add.
We booked early understanding the altitude and possibility of winter weather, but hoping that with most kids still in school there would be less traffic (Disneyland logic.) If we're lucky our gamble will pay off.
The suggestions of bikes, rental cars, and tour buses are all things I had not thought of and will research further. Thank you for those suggestions. We are definitely early risers and our plan was to generally start early and hit one major desirable attraction first-thing per day (again Disneyland logic.) Thank you for your confirmation that our plan may actually work.
4runnerguy, I would love to bring our older daughter with us on this trip and agree with you 100%. Unfortunately this is a busy time of year for our college sophomore. I hope one day she has the opportunity to first experience YS the way I did, when I was young on a summer break from school with friends.
suprz, please thank your son/daughter for their service to our nation from the Jones family.
Again thank you all for the tips and please keep them coming