diane, you really can't do the RT to Old Faithful in one day, b/c you won't have any time to spend there. The snowcoach literally arrives, unloads, then reloads for the trip back. I don' t think it stays more than an hour or so. Besides, there's plenty to see at OF. The geyser basin is really interesting. Spend at least one night there. We spent 3 nights there and I was never bored.

I wasn't suggesting you do the RT in one day. I just mentioned it b/c I didn't want you to think you'd have a lot of options as to what time you could travel in either direction.
It's basically the one option, morning from Mammoth and afternoon from OF. And you asked about going straight back to Bozeman from OF, which I don't think is feasible, unless you have a very late flight.

On our way from Mammoth to OF, we were delayed by about 1/2 hour b/c of a herd of bison on the road in front of us. So you have to allow time for unexpected delays, not to mention all the stops for photo ops.

panecott and others - Please excuse the input I mistakenly put in here that was meant for another thread, one in the USA forum. I guessed I goofed.

Anyway, e've been to Yellowstone so we know about the geysers in the Old Faithful and Yellowstone Lake area. Never got to the Mammoth part. Too far to drive. Would never think of going from Mammoth to Old Faithful area and back in one day.

Did think it sounded way to far and time consuming to go from Old Faithful area to Bozeman to catch a plane home. guess that means another day spent in Mammoth before heading to the airport.

sludick - Will check out what Yaktraks are. Never heard of them.

Yaktraks are traction cleat gizmos that you attach to your shoes. Here's a link: http://www.amazon.com/s/ref=nb_sb_ss...ks%2Caps%2C302

Trekking poles would have been a nice addition, but we made do without them.

Seeing the geysers without a crowd really changes the entire experience. Taking a hike along the trails, with snowy ground interrupted here and there by fumeroles, hotpots, and geysers - and no other people - was just spectacular.

About those bison that held us up - when they finally decided to move on, the first one to step off the trail went head over keester off into a deep snow bank. Hilarious!

sludick - We were there in first week of October and except for Old Faithful and Grand Canyon overlook, it wasn't particularly crowded.

Poor Bison slipping in front of you. Did he/she blush?