Hey Craig,
I only bought a rail pass the first time I came to Europe, because I didn't really know where I wanted to go and the flexibility was attractive.
It has been my experience since then, however, that it is simpler to buy tickets individually. But rail passes are sometimes nice.
I did find a railpass on the Rick Steves site for 5 days in Germany and the Czech Republic (http://www.ricksteves.com/rail/germany.htm#germben)for $270 per person with the saver fare (2 or more people traveling together at all times). This seems somewhat reasonable.
But remember that often you must pay reservation fees even when you have a railpass, especially on faster inter-city trains. If you are willing to take snail trains that stop every 10 minutes, you can avoid paying this fee, which is usually something like 4-5 Euros per person per train trip. This can easily add $30-40 onto the sticker price of the pass.
I did a little checking on the Deutsche Bahn website (www.bahn.de) and the cheapest tickets were as follows (all prices for you and your daughter together):
Frankfurt flughafen - Berlin on 5/25 for 172 Eur
Berlin - Prague 5/28 for 78 Eur
Prague - Regensburg 5/30 for 88 Eur
Regensberg - Munich 5/31 for 37 Eur
Munich - Heidelberg 6/2 for 78 Eur
Heidelberg - Frankfurt 6/3 for 38 Eur
This is actually six days, so if you only consider the 5 most expensive legs, this makes 454 Euros total, which is right around $600 at current exchange rates. This is almost exactly what you might expect to pay with your railpass. I'm actually quite shocked that the individual tickets were as expensive. This is probably due to the shockingly high cost of taking the train from Frankfurt to Berlin. I have only used a rail pass in Germany, and I had no idea that buying tickets individually could be so expensive!!!
If I were you, I would just buy the tickets as you go through Germany and CZ.
Good luck and have fun!
Geoff