We are planning vacation train travel for Aug 13 - 19th 2006, from San
Francisco, to Los Angeles, then east thru Santa Fe NM and
beyond...perhaps as far as Chicago IL.

What train routings can you suggest? Where may we book the train
travel, and by what date must this be done?

Thank you.

www.amtrak.com

You can take the Pacific Coast route from Emeryville (near San
Francisco) to Los Angeles, and from there transfer to the Sunrise
Express train to Santa Fe. However, from Santa Fe to Chicago is
probably unrealistic, because the Sunrise Express goes south through
Louisiana, etc. From the San Francisco Bay area to Chicago, you would
have to take the Empire Builder train through Salt Lake, Colorado,
etc., and on to Chi-town. Be forewarned, train travel in the United
States is unreasonably expensive.

As the other person who commented noted, the only interstate train
service in the US is offered through Amtrak. If you are coming from
Europe or another region with high-quality train service, please be
advised that long-distance rail travel in the U.S. is much less
desirable due to the cost, the inflexiblity of the schedule (usually
for long-distance routes there is only train per day), the frequency
of late and very late trains (due to the precedence given to freight
trains over passengers trains in the U.S.), and the lack of comfort
and privacy of non-sleeper car seats on overnight travel (and sleeper
cars are much more expensive).

Visit http://www.amtrak.com and plug in your proposed destinations and
dates and see what you come up with.  You might also check the status
of trains on this route on the current day or a few days before to get
an idea if they usually run or time or not (you might be surprised to
discover the long-distance trains are up to 6-8 hours late).

Note that the train from San Francisco to Los Angeles takes up almost
a whole day, and that it is utterly unrealistic to expect to go from
San Francisco to Los Angeles to Chicago in six days and expect to do
much of anything except sit on a train. If the train travel itself is
your goal, this is fine.  However, you might consider taking the train
to L.A. (which, though long, is at least a very scenic route in some
places), and then flying to New Mexico and then from there flying to
Chicago.

See also the website of the discount American airline Southwest,
http://www.iflyswa.com , which flies to Albuquerque and Chicago Midway
but doesn't show up on most other online flight searches.

All of this is not to necessarily discourage you from taking a train. 
If the goal is train travel itself, then do it by all means.  But you
should have a realistic view of rail travel in the U.S. and the ways
in which it differs from rail  travel in Europe (slow vs. fast).  You
won't be able to see all the sights on your schedule in six days by
train; you'll spend the majority of the time on the train itself.

As to booking the train travel, you can do so on amtrak.com itself and
pick up the tickets at the station.  There is no time limit in which
to book, provided that there are tickets available, although note that
the price can go up the longer you wait.