In Bay Area, only two travel

agents have their own bus run to Yellowstone: 喜悅假期 & Lassen. All others are seeling tickets of the two. Directly dealing with the two may get better deals. Take bus tour is a lot easier. From SJ to Y is two-day driving (one way). It's tired and boring if on your own. Furthermore, you are not familiar with the routs & stops for the first time, you'll spend a lot time on finding these. Booking hotels is another trouble in the high season.