I called the US Lufthansa sales office to try and add "rail and fly" to my SFO-MUC ticket that I recently booked on lufthansa US website as we are planning to visit Christkindmarkt on the weekend it opens. That's thanksgiving weekend in the US.

The agent was very helpful. 100 Euro for a round trip 1st class ticket (50 Eu for 2nd class). It's converted to US$ at the current exchange rate and charged to your US credit card. Once booked, the agent says he issues you a code and you can retrieve your ticket at any DBB vending machine.

*** no german address needed ***

I haven't booked it yet as I'm still pricing out tickets on the bahn.de website. Booking a month in advance, the discounted price 29 Euro (round trip 2nd class) or 60.75 Eu (1st class). The downside is that they are for fixed trains.

What is attracting me to the Rail&Fly ticket is that you can take any train one day before or on the day of your flight. Hopefully I read it correctly! I'm still deciding whether to save the money or spend a little more and have flexibility.