Stay somewhere between Caesar’s and Mandalay Bay so you can walk everywhere. Too many restaurants to name, but make sure to take her to a few decent ones(I recommend happy hour at the forum shoppes). You can always find other discount shoes while you are there.
Aquarium at Mandalay Bay, Big Cats at MGM, Gondola ride at the Venetian, Ferris Wheel behind the Linq, Fountains at Bellagio, plenty more, just google and pick whatever sounds fun.