I was there last summer after my backpacking trip to the Winds. Since I was going light due to backpacking, I only took my 18-200mm A mount lens. Yellowstone is one of those places where you need wider angle for many landscapes (though not as many as one might initially think) and a long lens for the wildlife (unless you want them to be seen as little points).
That is 24MP on an APS-C, so those pixels are very close together. I wouldn't want to depend on cropping to get the picture you want. If you end up with just one lens for Yellowstone, I might consider a longer one and then shoot multiple images to stitch together for landscapes.