Plus, make sure the bus is running on the day you're looking at.....I did this journey last year, and found out on a Sat morning while waiting for the bus in Lone Pine that the bus schedule they gave me over the phone was only valid Monday through Friday. Because of light weekend travel, they decided to halt the Sat service---with no notice or anything.....I ended up hitching a ride to Mammoth. Not the way I planned it, but it turned out all right. From Mammoth, I hopped on YARTS to Yosemite Valley.