Almost anywhere you go fishing is crowded. That applies not only streams and smaller still waters, but roads going there (travel as early in the day as possible). The best way to avoid crowds is to walk away from easily accessed waters once you reach them. That means try such as Fall River Basin, Lewis River between Shoshone and Lewis Lakes, second meadow above on Slough Creek, Cache Creek area on the Lamar River, Black Canyon of the Yellowstone and so forth. Even in those places you will have company, but to a lesser amount. For almost all streams presenting terrestrial insect patterns is the best way to fishing success.