Many thanks to both of you for your response. I have three months to spend on a tour and I am inclined towards the TA. I guess my only concern was whether it was too hard for a novice tourer like myself.
Also I've heard it said that the TA is better traveled West to East. Is there really any difference? I live on the East coast, so I'm planning to go West.
Three months is enough for most people.
My opinion is that due to weather factors direction of travel depends on when you go as much as anything. If you want to get a started early in the season I'd start in the east. If you want to start a bit later W-E might be better. You are most likely to avoid both the worst heat and the worst cold with one of those two options.
I started on June 11th in the west and it worked out very well. The only drawback is that some years McKenzie pass may open in mid to late June (or even more rarely July). You can take Santiam Pass, but it would be a shame to miss Mckenzie.
Another factor to consider is where you live if you are close to one end or the other. I much prefer to finish my tours close to home. That way I can get air travel out of the way up front. It is much easier to plan for travel at a fixed start date rather than a flexible finish date.
Don't believe the folks who tell you about the prevailing westerly winds. The winds in the Great Plains are most often out of the Southeast in Summer and the TA crosses the Plains in a generally SE direction. So we found that there was an advantage for E-W there but I wouldn't make my choice based on the wind for this route.
One other thing... we found the steep climbs in the Appalachians and Ozarks to be the hardest of the trip. The ones in the west were very long but not as steep. We were happy to have the Appalachians later in the trip when we were fully road hardened.