here's a good resource for you: http://www.maxwaugh.com/yellowstone/map.php

there are all the species in that loop/area you discuss. The reason I say the madison out of west yellowstone is because you mention elk as your goal. this area has lots of elk and you will be able to find them and get quite close. You will see elk from the north but you man not be able to get very close to them. . .