Las Vegas is Hermes heaven!!!! You can definitely walk in as a newbie and get a KDT (a CDC is much harder) amongst other things. If you go to the Crystals, ask for Frances, she's an angel...she can make miracles happen! I got my first hermes scarves there, then went on to get my first kelly, first birkin... from her, and I was just a tourist from SF. Now she's my go to SA.
Between the 3 stores, you can definitely score a KDT or other yummy goodies, things you didn't even know you wanted. Go into the boutique with an open mind, just in case there isn't a KDT around, but there might be a rivale or kelly dog or CDC... a clic clac paired with a couple of enamels would make a nice souvenir too.
H at the Bellagio is good and the one at Encore is a great backup. Good luck to you. and have fun!!!