i've seen a map posted before, but in general terms.
For the regular decks, You have a short moving walkway that takes you from the deck to the center "hub", then past bag check there are 3 sections of moving walkways into Citywalk. (That doesn't include the walking you need to do from your parking spot to the 'front' of the deck, and any escalators/stairs or moving walkways you need to take to get to the bridge to the hub).
From Valet, You just go up the escalator and have only 1 moving walkway section into Citywalk. You also do your car drop-off/pickup almost right in front of the escalator.
Its a MUCH shorter distance..... however time-wise leaving it can vary and sometimes be competative with regular or preferred parking since it could potentially take some time for them the fetch your car when you leave, especially if there is a line.