As I alluded to in my previous post, trains can be a cheap and easy way to move from place to place without having to drive anywhere if you are a single traveler. According to Deutche Bahn, it is not uncommon for business travelers to use the train to move around the country. Considering that the longest common route without leaving Germany is about 10 hours, that is possible. Again, according to the rail line, business travelers are more likely to purchase 1st class tickets but I believe that 2nd class is more likely. (Sounds familiar to US air carrier advertising).
As a N. American or S. American citizen, you can purchase a railpass which comes in dozens of different options or go point to point. Frommer's put out a Europe by Rail guide this year that is about 2" thick full of connections and railpass information. I'll try to sum up the basics.
The 2 main flavors of passes are a standard pass and a flexipass. Both passes are good for a certain number of days ie 10, 15 ect. The standard pass has these days as consecutive and the "flexi" pass uses only days of travel over a 2 month period. Believe it or not, the "flexi" passes are cheaper and can become even more cheaper if you restrict your travels to 3, 4, or 5 countries. I purchaced a "flexi" pass as I will be traveling by rail on my time off rather than work but these passes would work for business travel also. The main reason to get a pass is if you have to make long haul (usually 4+ hr.) trips accross country multiple times. If you are moving around but in a close area or making very few long trips, a pass doesn't pay off with cost savings and you are better served buying point to point. The passes can only be sent to overseas addresses or available in limited locations in Europe for a premium so best to investigate prior to arrival.
My experience with Deutche Bahn has been good so far. Most of the employee's I've encountered have been friendly and can speak at least some English. Most appear to be pretty fluent. The Swiss Bahn is also very nice. I haven't had a problem with trains being late or not running at all. The first class cabin on most trains is very quiet and very empty. This may be because I am traveling on weekends or most travelers taking the train are purchasing 2nd class tickets. During the summer season, I imagine that the trains will be packed with tourists particularly the July-August months. I have been on several trains where 2nd class is full to the gills and 1st class is nearly void of people. As the difference on some routes is 10 to 20 Euro's, ask about 1st class before taking the 2nd class seat.
There are different types of trains but most business travelers will be interested in the ICE and the IC. IC stands for Inter City (the E is Express). These are the fast modern trains that make the advertisements in all the papers. The IC/ICE makes few stops and will move between most major cities. I have found that most of these trains usually have some connections in Koln (Cologne)/Dusseldorf, Mannheim, Munchen (Munich), Berlin, and Stuttgart. I highly recommend paying attention to what type of train you are on as the S trains are much slower.
For example, there is an S train leaving from Stuttgart to Heidelburg and an ICE train leaving 45 minutes later. I got to Heidelburg on the ICE train and beat the S train by over 30 minutes. The S trains are the standard commuter trains but if you need to get to or from a smaller city, that's the service. I have had good luck using the Deutche Bahn website to view connections and travel times. www.bahn.de. There is an english section under the international guests tab.