20天的美西行程是否合理？请高手指点指点。

Day1：Los angeles
Day2：Los angeles to Las vegas
Day3：Las vegas to Idaho falls
Day4：Yellowstone： Bozeman住宿；
Day5：Yellowstone： Cody住宿；
Day6：Yellowstone： Jackson住宿；
Day7：Yellowstone to Salt lake city
Day8：Salt lake city to Bishop
Day9：Yosemite： Mariposa住宿
Day10：Yosemite
Day11：Napa
Day12：Napa to San Francisco
Day13：San Francisco
Day14：Monterey to Morro Bay
Day15：Morro Bay to Oxnard
Day16：Oxnard to Sedona
Day17：Grand Canyon
Day18：Flagstaff to Las vegas
Day19：Las vegas；
Day20：Las vegas to Los angeles；
Day21：Los angeles